Combinations of anti-staphylococcus aureus antibodies

ABSTRACT

The present disclosure is directed to anti-Staphylococcus aureus antibody combinations including combinations of antibodies that bind to S. aureus alpha toxin (AT) protein, clumping factor A protein (ClfA), and/or at least one leukotoxin protein. Methods of treating and preventing infections comprising administering the antibody combinations are also provided herein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of U.S. ProvisionalApplication No. 62/833,297, filed Apr. 12, 2019, and U.S. ProvisionalApplication No. 62/743,490, filed Oct. 9, 2018, each of which is herebyincorporated by reference herein in its entirety.

SEQUENCE LISTING

The content of the electronically submitted sequence listing (Name:2943_1020002_SeqListing_ST25.txt; Size: 81,662 bytes; and Date ofCreation: Oct. 8, 2019) is hereby incorporated by reference.

BACKGROUND

Infections caused by antimicrobial resistant (AMR) bacterial pathogensare an increasing threat to public health. The ongoing AMR epidemic hasbeen fueled, in part, by empiric broad spectrum antibiotic therapy. Thishas led to the exploration of pathogen specific methods, includingmonoclonal antibodies (mAbs), to prevent or treat serious bacterialinfections. Numerous monoclonal antibodies are currently in developmentfor the prevention or treatment of antibiotic resistant bacterialinfections (see, e.g., DiGiandomenico, A., and B. R. Sellman, Curr.Opin. Microbiol., 27: 78-85 (2015)). Such passive immunizationstrategies provide an immediate and potent immunoglobulin responseagainst the target pathogen. Ideally, the monoclonal antibody ormonoclonal antibody cocktail provides multiple mechanisms of action toneutralize key bacterial virulence mechanisms and augment the hostinnate immune response, thus providing the greatest opportunity forclinical success.

Staphylococcus aureus is a bacterial pathogen that causes a wide arrayof diseases including skin and soft tissue infections, endocarditis,osteomyelitis, pneumonia, and bacteremia (Lowy, F. D., N. Engl. J. Med.,339(8): 520-32 (1998)). Preclinical studies indicate monoclonalantibody-based approaches hold promise for prophylaxis and adjunctivetherapy against S. aureus infections (see, e.g., Hazenbos et al., PLoSPathog., 9(10):e1003653. doi: 10.1371/journal.ppat.10036532013 (2013);Rouha, H., MAbs, 7(1): 243-254 (2015); Foletti et al., J. Mol. Biol.,425(10): 1641-1654 (2013); Karauzum et al., J Biol Chem., 287(30):25203-15 (2012); and Hua et al., Antimicrob Agents Chemother., 58(2):1108-17 (2014)). However, treatment with individual antibodies may notbe sufficient to address all Staphylococcus aureus infections. Thus,there remains a need for compositions and methods for treatingStaphylococcus aureus infections, particularly infections that areresistant to currently-available antibiotics and that provide broaddisease and strain coverage. The present disclosure provides suchcompositions and methods.

BRIEF SUMMARY OF THE INVENTION

As demonstrated herein, combinations of antibodies that target severaldifferent bacterial virulence factors via complementary mechanism ofaction can provide broad strain coverage and broad disease coverage.Exemplary animal models supporting the breadth of strain and diseasecoverage encompassed by the combinations of antibodies provided hereinis provided in FIG. 1.

Provided herein are methods of treating or preventing a Staphylococcusaureus (S. aureus) infection in a subject comprising administering tothe subject (a) an antibody or antigen-binding fragment thereof thatbinds to S. aureus alpha toxin (AT), (b) an antibody or antigen-bindingfragment thereof that binds to S. aureus clumping factor A (ClfA), and(c) an antibody or antigen-binding fragment thereof that binds to atleast one S. aureus leukotoxin.

Provided herein are also methods of treating or preventing a S. aureusinfection in a subject comprising administering to the subject anantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin and (a) an antibody or antigen-binding fragmentthereof that binds to S. aureus alpha toxin (AT) or (b) an antibody orantigen-binding fragment thereof that binds to S. aureus clumping factorA (ClfA).

Provided herein are also compositions comprising (a) an antibody orantigen-binding fragment thereof that binds to S. aureus AT, (b) anantibody or antigen-binding fragment thereof that binds to S. aureusClfA, and (c) an antibody or antigen-binding fragment thereof that bindsto at least one S. aureus leukotoxin.

Provided herein are also compositions comprising an antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin and (a) an antibody or antigen-binding fragment thereof thatbinds to S. aureus AT or (b) an antibody or antigen-binding fragmentthereof that binds to S. aureus ClfA.

In certain instances, the composition is for use in treating orpreventing a S. aureus infection in a subject.

Provided herein are also antibodies and antigen-binding fragmentsthereof that bind to S. aureus AT for use in treating or preventing a S.aureus infection in a subject in combination with an antibody orantigen-binding fragment thereof that binds to S. aureus ClfA and anantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin.

Provided herein are also antibodies and antigen-binding fragmentsthereof that bind to S. aureus ClfA for use in treating or preventing aS. aureus infection in a subject in combination with an antibody orantigen-binding fragment thereof that binds to S. aureus AT and anantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin.

Provided herein are also antibodies and antigen-binding fragmentsthereof that bind to at least one S. aureus leukotoxin for use intreating or preventing a S. aureus infection in a subject in combinationwith an antibody or antigen-binding fragment thereof that binds to S.aureus AT and/or an antibody or antigen-binding fragment thereof thatbinds to S. aureus ClfA.

In certain instances, the composition is used in the preparation of amedicament for treating or preventing a S. aureus infection in asubject.

Provided herein are also uses of an antibody or antigen-binding fragmentthereof that binds to S. aureus AT in the preparation of a medicamentfor treating or preventing a S. aureus infection in a subject incombination with an antibody or antigen-binding fragment thereof thatbinds to S. aureus ClfA and an antibody or antigen-binding fragmentthereof that binds to at least one S. aureus leukotoxin.

Provided herein are also uses of an antibody or antigen-binding fragmentthereof that binds to S. aureus ClfA in the preparation of a medicamentfor treating or preventing a S. aureus infection in a subject incombination with an antibody or antigen-binding fragment thereof thatbinds to S. aureus AT and an antibody or antigen-binding fragmentthereof that binds to at least one S. aureus leukotoxin.

Provided herein are also uses of an antibody or antigen-binding fragmentthereof that binds to at least one S. aureus leukotoxin in thepreparation of a medicament for treating or preventing a S. aureusinfection in a subject in combination with an antibody orantigen-binding fragment thereof that binds to S. aureus AT and/or anantibody or antigen-binding fragment thereof that binds to S. aureusClfA.

In certain instances of the method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the antibodyor antigen-binding fragment thereof that binds to S. aureus AT binds tothe same S. aureus AT epitope as an antibody comprising a VH comprisingthe amino acid sequence of SEQ ID NO:19 and a VL comprising the aminoacid sequence of SEQ ID NO:33. In certain instances, the antibody orantigen-binding fragment thereof that binds to S. aureus ATcompetitively inhibits binding of an antibody comprising a VH comprisingthe amino acid sequence of SEQ ID NO:19 and a VL comprising the aminoacid sequence of SEQ ID NO:33 to S. aureus AT. In certain instances, theantibody or antigen-binding fragment thereof that binds to S. aureus ATcomprises a variable heavy chain (VH) complementarity determining region(CDR) 1 comprising the amino acid sequence of SEQ ID NO:1, a VH CDR2comprising the amino acid sequence of SEQ ID NO:2, a VH CDR3 comprisingthe amino acid sequence of SEQ ID NO:3, a variable light chain (VL) CDR1comprising the amino acid sequence of SEQ ID NO:10, a VL CDR2 comprisingthe amino acid sequence of SEQ ID NO:11, and a VL CDR3 comprising theamino acid sequence of SEQ ID NO:12. In certain instances, the antibodyor antigen-binding fragment thereof that binds to S. aureus AT comprisesa VH comprising the amino acid sequence of SEQ ID NO:19. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus AT comprises a VL comprising the amino acid sequence of SEQID NO:33. In certain instances, the antibody or antigen-binding fragmentthereof that binds to S. aureus AT comprises a heavy chain comprisingthe amino acid sequence of SEQ ID NO:47. In certain instances, theantibody or antigen-binding fragment thereof that binds to S. aureus ATcomprises a light chain comprising the amino acid sequence of SEQ IDNO:52. In certain instances, the antibody or antigen-binding fragmentthereof that binds to S. aureus AT comprises the VH CDR1, VH CDR2, VHCDR3, VL CDR1, VL CDR2, and VL CDR3 of MEDI4893. In certain instances,the CDRs are the Kabat-defined CDRs, the Chothia-defined CDRs, or theAbM-defined CDRs. In certain instances, the antibody or antigen-bindingfragment that binds to S. aureus AT further comprises a heavy chainconstant region. In certain instances, the heavy chain constant regionis selected from the group consisting of human immunoglobulin IgG₁,IgG₂, IgG₃, IgG₄, IgA₁, and IgA₂ heavy chain constant regions. Incertain instances, the heavy chain constant region is a human IgG₁constant region. In certain instances, the antibody or antigen-bindingfragment that binds to S. aureus AT further comprises a light chainconstant region. In certain instances, the light chain constant regionis selected from the group consisting of human immunoglobulin IgGκ andIgGλ light chain constant regions. In certain instances, the light chainconstant region is a human IgGκ light chain constant region. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus AT is an IgG antibody or antigen-binding fragment thereof.In certain instances, the antibody or antigen-binding fragment thereofthat binds to S. aureus AT comprises an Fc region that has beenengineered to improve half-life. In certain instances, the antibody orantigen-binding fragment thereof that binds to S. aureus AT comprises anFc region with a YTE mutation. In certain instances, the antibody orantigen-binding fragment that binds to S. aureus AT is a monoclonalantibody or antigen-binding fragment. In certain instances, the antibodyor antigen-binding fragment that binds to S. aureus AT is a full-lengthantibody. In certain instances, the antibody or antigen-binding theantigen-binding fragment comprises a Fab, Fab′, F(ab′)₂, single chain Fv(scFv), disulfide linked Fv, intrabody, IgGΔCH2, minibody, F(ab′)₃,tetrabody, triabody, diabody, DVD-Ig, Fcab, mAb², (scFv)₂, or scFv-Fc.In certain instances, the antibody or antigen-binding fragment thereofthat binds to S. aureus AT has an affinity of 80-100 pM for S. aureusAT.

In certain instances of the method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the antibodyor antigen-binding fragment thereof that binds to S. aureus ClfA bindsto the same S. aureus ClfA epitope as an antibody comprising a VHcomprising the amino acid sequence of SEQ ID NO:20 and a VL comprisingthe amino acid sequence of SEQ ID NO:34. In certain instances, theantibody or antigen-binding fragment thereof that binds to S. aureusClfA competitively inhibits binding of an antibody comprising a VHcomprising the amino acid sequence of SEQ ID NO:20 and a VL comprisingthe amino acid sequence of SEQ ID NO:34 to S. aureus ClfA. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus ClfA comprises a VH CDR1 comprising the amino acid sequenceof SEQ ID NO:4, a VH CDR2 comprising the amino acid sequence of SEQ IDNO:5, a VH CDR3 comprising the amino acid sequence of SEQ ID NO:6, a VLCDR1 comprising the amino acid sequence of SEQ ID NO:13, a VL CDR2comprising the amino acid sequence of SEQ ID NO:14, and a VL CDR3comprising the amino acid sequence of SEQ ID NO:15. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus ClfA comprises a VH comprising the amino acid sequence ofSEQ ID NO:20. In certain instances, the antibody or antigen-bindingfragment thereof that binds to S. aureus ClfA comprises a VL comprisingthe amino acid sequence of SEQ ID NO:34. In certain instances, theantibody or antigen-binding fragment thereof that binds to S. aureusClfA comprises a heavy chain constant domain comprising the amino acidsequence of CSYHLC (SEQ ID NO:55). In certain instances, the heavy chainconstant domain comprises the amino acid sequence of MHEACSYHLCQKSLSLS(SEQ ID NO:56). In certain instances, the antibody or antigen-bindingfragment thereof that binds to S. aureus ClfA comprises a heavy chaincomprising the amino acid sequence of SEQ ID NO:49. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus ClfA comprises a light chain comprising the amino acidsequence of SEQ ID NO:53. In certain instances, the antibody orantigen-binding fragment thereof that binds to S. aureus ClfA comprisesthe VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 ofSAR114-N3Y. In certain instances, the antibody or antigen-bindingfragment thereof that binds to S. aureus ClfA comprises the VH CDR1, VHCDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of 11H10, SAR72, SAR80,SAR113, SAR132, SAR352, SAR372, SAR510, SAR547, SAS1, SAS19, or SAS203.In certain instances, the CDRs are the Kabat-defined CDRs, theChothia-defined CDRs, or the AbM-defined CDRs. In certain instances, theantibody or antigen-binding fragment thereof that binds to S. aureusClfA comprises a VH and a VL, wherein the VH comprises the amino acidsequence set forth in any one of SEQ ID NOs:21-31 and 68. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus ClfA comprises a VH and a VL, wherein the VL comprises theamino acid sequence set forth in any one of SEQ ID NOs: 35-45 and 69. Incertain instances, the antibody or antigen-binding fragment thereof thatbinds to S. aureus ClfA comprises VH and VL sequences comprising theamino acid sequences set forth in (a) SEQ ID NOs:21 and 35, respectively(b) SEQ ID NOs:22 and 36, respectively, (c) SEQ ID NOs:23 and 37,respectively, (d) SEQ ID NOs:24 and 38, respectively, (e) SEQ ID NOs:25and 39, respectively, (f) SEQ ID NOs:26 and 40, respectively, (g) SEQ IDNOs:27 and 41, respectively, (h) SEQ ID NOs:28 and 42, respectively (i)SEQ ID NOs:29 and 43, respectively, (j) SEQ ID NOs:30 and 44,respectively, (k) SEQ ID NOs:31 and 45, respectively, or (1) SEQ ID NOs:68 and 69, respectively. In certain instances, the antibody orantigen-binding fragment that binds to S. aureus ClfA further comprisesa heavy chain constant region. In certain instances, the heavy chainconstant region is selected from the group consisting of humanimmunoglobulin IgG₁, IgG₂, IgG₃, IgG₄, IgA₁, and IgA₂ heavy chainconstant regions. In certain instances, the heavy chain constant regionis a human IgG₁ constant region. In certain instances, the antibody orantigen-binding fragment that binds to S. aureus ClfA further comprisesa light chain constant region. In certain instances, the light chainconstant region is selected from the group consisting of humanimmunoglobulin IgGκ and IgGλ light chain constant regions. In certaininstances, the light chain constant region is a human IgGκ light chainconstant region. In certain instances, the antibody or antigen-bindingfragment that binds to S. aureus ClfA comprises a mutation that extendshalf-life relative to the same antibody without the mutation in humanFcRn mice. In certain instances, the antibody or antigen-bindingfragment that binds to S. aureus ClfA comprises a mutation that extendshalf-life relative to the same antibody without the mutation, andwherein the mutation does not inhibit OPK activity relative to the sameantibody or antigen-binding fragment the mutation. In certain instances,the antibody or antigen-binding fragment that binds to S. aureus ClfA isa monoclonal antibody or antigen-binding fragment. In certain instances,the antibody or antigen-binding fragment that binds to S. aureus ClfA isa full-length antibody. In certain instances, the antibody orantigen-binding fragment that binds to S. aureus ClfA is anantigen-binding fragment. In certain instances, the antigen-bindingfragment comprises a Fab, Fab′, F(ab′)₂, single chain Fv (scFv),disulfide linked Fv, intrabody, IgGΔCH2, minibody, F(ab′)₃, tetrabody,triabody, diabody, DVD-Ig, Fcab, mAb², (scFv)₂, or scFv-Fc. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto S. aureus ClfA has IC50s for ClfA001, ClfA002, and ClfA004 in afibrinogen binding inhibition assay that are within 2 μg/ml of eachother. In certain instances, the antibody or antigen-binding fragmentthereof that binds to S. aureus ClfA has IC50s for ClfA001, ClfA002, andClfA004 in a fibrinogen binding inhibition assay that are all between 1μg/ml and 5 μg/ml. In certain instances, the antibody or antigen-bindingfragment thereof that binds to S. aureus ClfA has binding affinities(K_(D)) for ClfA001, ClfA002, and ClfA004 that are all between 200 and350 pM. In certain instances, the antibody or antigen-binding fragmentthereof that binds to S. aureus ClfA has binding affinities (K_(D)) ofless than 1 nM for all ClfA genotypes. In certain instances, theantibody or antigen-binding fragment that binds to S. aureus ClfA has amonomer purity that decreases by no more than 5% after exposure of theantibody or antigen-binding fragment to conventional white light at2kLux/hr at 23° C. for 14 days.

In certain instances of the method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the antibodyor antigen-binding fragment thereof that binds to at least one S. aureusleukotoxin binds to LukF, LukD, and/or HlgB, and/or wherein the antibodyor antigen-binding fragment thereof neutralizes LukF, LukD, and/or HlgB.In certain instances, the antibody or antigen-binding fragment thereofthat binds to at least one S. aureus leukotoxin binds to LukF, LukD, andHlgB, and/or wherein the antibody or antigen-binding fragment thereofneutralizes LukF, LukD, and HlgB. In certain instances, the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin binds to the same S. aureus leukotoxin epitope as an antibodycomprising a VH comprising the amino acid sequence of SEQ ID NO:32 and aVL comprising the amino acid sequence of SEQ ID NO:46. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto at least one S. aureus leukotoxin competitively inhibits binding ofan antibody comprising a VH comprising the amino acid sequence of SEQ IDNO:32 and a VL comprising the amino acid sequence of SEQ ID NO:46 to theS. aureus leukotoxin. In certain instances, the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin comprises a VHCDR1 comprising the amino acid sequence of SEQID NO:7, a VH CDR2 comprising the amino acid sequence of SEQ ID NO:8, aVH CDR3 comprising the amino acid sequence of SEQ ID NO:9, a VL CDR1comprising the amino acid sequence of SEQ ID NO:16, a VL CDR2 comprisingthe amino acid sequence of SEQ ID NO:17, and a VL CDR3 comprising theamino acid sequence of SEQ ID NO:18. In certain instances, the antibodyor antigen-binding fragment thereof that binds to at least one S. aureusleukotoxin comprises a VH comprising the amino acid sequence of SEQ IDNO:32. In certain instances, the antibody or antigen-binding fragmentthereof that binds to at least one S. aureus leukotoxin comprises a VLcomprising the amino acid sequence of SEQ ID NO:46. In certaininstances, the antibody or antigen-binding fragment thereof that bindsto at least one S. aureus leukotoxin comprises a heavy chain comprisingthe amino acid sequence of SEQ ID NO:50. In certain instances, theantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin comprises a light chain comprising the amino acidsequence of SEQ ID NO:54. In certain instances, the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin comprises the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2,and VL CDR3 of SAN481-SYT. In certain instances, the CDRs are theKabat-defined CDRs, the Chothia-defined CDRs, or the AbM-defined CDRs.In certain instances, the antibody or antigen-binding fragment thatbinds to at least one S. aureus leukotoxin further comprises a heavychain constant region. In certain instances, the heavy chain constantregion is selected from the group consisting of human immunoglobulinIgG₁, IgG₂, IgG₃, IgG₄, IgA₁, and IgA₂ heavy chain constant regions. Incertain instances, the heavy chain constant region is a human IgG₁constant region. In certain instances, the antibody or antigen-bindingfragment that binds at least one S. aureus leukotoxin further comprisesa light chain constant region. In certain instances, the light chainconstant region is selected from the group consisting of humanimmunoglobulin IgGκ and IgGλ light chain constant regions. In certaininstances, the light chain constant region is a human IgGκ light chainconstant region. In certain instances, the antibody or antigen-bindingfragment thereof that binds to at least one S. aureus leukotoxin is anIgG antibody or antigen-binding fragment thereof. In certain instances,the antibody or antigen-binding fragment thereof that binds to at leastone S. aureus leukotoxin comprises an Fc region that has been engineeredto improve half-life. In certain instances, the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin comprises an Fc region with a YTE mutation. In certaininstances, the antibody or antigen-binding fragment that binds to atleast one S. aureus leukotoxin is a monoclonal antibody orantigen-binding fragment. In certain instances, the antibody orantigen-binding fragment that binds to at least one S. aureus leukotoxinis a full-length antibody. In certain instances, the antibody orantigen-binding fragment that binds to at least one S. aureus leukotoxinis an antigen-binding fragment. In certain instances, theantigen-binding fragment comprises a Fab, Fab′, F(ab′)₂, single chain Fv(scFv), disulfide linked Fv, intrabody, IgGΔCH2, minibody, F(ab′)₃,tetrabody, triabody, diabody, DVD-Ig, Fcab, mAb², (scFv)₂, or scFv-Fc.In certain instances, the antibody or antigen-binding fragment thereofthat binds to at least one S. aureus leukotoxin has an affinity of lessthan 75 pM for S. aureus LukF, LukD, and HlgAB. In certain instances,the antibody or antigen-binding fragment thereof that binds to at leastone S. aureus leukotoxin has similar binding affinities for LukF, LukD,and HIgB.

In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the S. aureusinfection is sepsis. In certain instances of a method, composition,antibody or antigen-binding fragment thereof, or use provided herein,the S. aureus infection is bacteremia. In certain instances of a method,composition, antibody or antigen-binding fragment thereof, or useprovided herein, the S. aureus infection is pneumonia. In certaininstances of a method, composition, antibody or antigen-binding fragmentthereof, or use provided herein, the S. aureus infection is pneumoniathe S. aureus infection is ICU pneumonia. In certain instances of amethod, composition, antibody or antigen-binding fragment thereof, oruse provided herein, the S. aureus infection is a skin or soft tissueinfection (SSTI). In certain instances of a method, composition,antibody or antigen-binding fragment thereof, or use provided herein,the S. aureus infection is a diabetic infection of the lower limbs. Incertain instances of a method, composition, antibody or antigen-bindingfragment thereof, or use provided herein, the S. aureus infection is adiabetic foot ulcer (DFU). In certain instances, the DFU is uninfected.In certain instances, the DFU is infected. In certain instances, the DFUis a grade 1, 2 or 3 DFU. In certain instances of a method, composition,antibody or antigen-binding fragment thereof, or use provided herein,the S. aureus infection is a bone or joint infection. In certaininstances of a method, composition, antibody or antigen-binding fragmentthereof, or use provided herein, the S. aureus infection is a jointinfection, a device infection, a wound infection, a surgical siteinfection, or osteomyelitis.

In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the subject isa surgical subject.

In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the S. aureusinfection comprises antibiotic-resistant S. aureus.

In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the subjecthas diabetes. In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the subject ishuman.

In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the treatingor preventing an S. aureus infection comprises inhibiting S. aureusagglutination, toxin neutralization, inducing opsonophagocytosis,inhibiting S. aureus fibrinogen binding, inhibiting S. aureusagglutination, inhibiting thromboembolic lesion formation, inhibiting S.aureus-associated sepsis, or any combination of the foregoing.

In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the antibodyor antigen-binding fragment thereof that binds to S. aureus AT and theantibody or antigen-binding fragment thereof that binds to S. aureusClfA are administered in the same pharmaceutical composition. In certaininstances of a method, composition, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT and the antibody orantigen-binding fragment thereof that binds to S. aureus ClfA areadministered in the separate pharmaceutical compositions. In certaininstances of a method, composition, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT and the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin are administered in the same pharmaceutical composition. Incertain instances of a method, composition, antibody or antigen-bindingfragment thereof, or use provided herein, the antibody orantigen-binding fragment thereof that binds to S. aureus AT and theantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin are administered in the separate pharmaceuticalcompositions. In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the antibodyor antigen-binding fragment thereof that binds to S. aureus ClfA and theantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin are administered in the same pharmaceuticalcomposition. In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the antibodyor antigen-binding fragment thereof that binds to S. aureus ClfA and theantibody or antigen-binding fragment thereof that binds to at least oneS. aureus leukotoxin are administered in the separate pharmaceuticalcompositions. In certain instances of a method, composition, antibody orantigen-binding fragment thereof, or use provided herein, the separatepharmaceutical compositions are administered simultaneously. In certaininstances of a method, composition, antibody or antigen-binding fragmentthereof, or use provided herein, the separate pharmaceuticalcompositions are administered sequentially. In certain instances of amethod, composition, antibody or antigen-binding fragment thereof, oruse provided herein, the antibody or antigen-binding fragment thereofthat binds to S. aureus AT, the antibody or antigen-binding fragmentthereof that binds to S. aureus ClfA, and the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin are administered in the same pharmaceutical composition.

Provided herein are also methods of treating or preventing a S. aureusinfection in a subject with diabetes comprising administering to thesubject an antibody or antigen-binding fragment thereof that binds to S.aureus AT.

Provided herein are also antibodies or antigen-binding fragments thereofthat bind to S. aureus AT for use in treating or preventing a S. aureusinfection in a subject with diabetes.

Provided herein are also uses of an antibody or antigen-binding fragmentthereof that binds to S. aureus AT in the preparation of a medicamentfor treating or preventing a S. aureus infection in a subject withdiabetes.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT binds to the same S. aureusAT epitope as an antibody comprising a VH comprising the amino acidsequence of SEQ ID NO:19 and a VL comprising the amino acid sequence ofSEQ ID NO:33.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT competitively inhibitsbinding of an antibody comprising a VH comprising the amino acidsequence of SEQ ID NO:19 and a VL comprising the amino acid sequence ofSEQ ID NO:33 to S. aureus AT.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises a VH CDR1comprising the amino acid sequence of SEQ ID NO:1, a VH CDR2 comprisingthe amino acid sequence of SEQ ID NO:2, a VH CDR3 comprising the aminoacid sequence of SEQ ID NO:3, a VL CDR1 comprising the amino acidsequence of SEQ ID NO:10, a VL CDR2 comprising the amino acid sequenceof SEQ ID NO:11, and a VL CDR3 comprising the amino acid sequence of SEQID NO:12.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises a VH comprisingthe amino acid sequence of SEQ ID NO:19.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises a VL comprisingthe amino acid sequence of SEQ ID NO:33.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises a heavy chaincomprising the amino acid sequence of SEQ ID NO:47.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises a light chaincomprising the amino acid sequence of SEQ ID NO:52.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises the VH CDR1, VHCDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of MEDI4893. In certaininstances, the CDRs are the Kabat-defined CDRs, the Chothia-definedCDRs, or the AbM-defined CDRs.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment that binds to S. aureus AT further comprises a heavy chainconstant region. In certain instances, the heavy chain constant regionis selected from the group consisting of human immunoglobulin IgG₁,IgG₂, IgG₃, IgG₄, IgA₁, and IgA₂ heavy chain constant regions. Incertain instances, the heavy chain constant region is a human IgG₁constant region.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment that binds to S. aureus AT further comprises a light chainconstant region. In certain instances, the light chain constant regionis selected from the group consisting of human immunoglobulin IgGκ andIgGλ light chain constant regions. In certain instances, the light chainconstant region is a human IgGκ light chain constant region.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT is an IgG antibody orantigen-binding fragment thereof.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises an Fc region thathas been engineered to improve half-life.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises an Fc region witha YTE mutation.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment that binds to S. aureus AT is a monoclonal antibody orantigen-binding fragment.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment that binds to S. aureus AT is a full-length antibody.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment that binds to S. aureus AT is an antigen-binding fragment. Incertain instances, the antigen-binding fragment comprises a Fab, Fab′,F(ab′)₂, single chain Fv (scFv), disulfide linked Fv, intrabody,IgGΔCH2, minibody, F(ab′)₃, tetrabody, triabody, diabody, DVD-Ig, Fcab,mAb², (scFv)₂, or scFv-Fc.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the antibody or antigen-bindingfragment thereof that binds to S. aureus AT has an affinity of 80-100 pMfor S. aureus AT.

In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the S. aureus infection is sepsis. Incertain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the S. aureus infection is bacteremia.In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the S. aureus infection is pneumonia.In certain instances of a method, antibody or antigen-binding fragmentthereof, or use provided herein, the S. aureus infection is ICUpneumonia. In certain instances of a method, antibody or antigen-bindingfragment thereof, or use provided herein, the S. aureus infection is aSSTI. In certain instances of a method, antibody or antigen-bindingfragment thereof, or use provided herein, the S. aureus infection is adiabetic infection of the lower limbs. In certain instances of a method,antibody or antigen-binding fragment thereof, or use provided herein,the S. aureus infection is a DFU. In certain instances, the DFU isuninfected. In certain instances, the DFU is infected. In certaininstances, the DFU is a grade 1, 2 or 3 DFU. In certain instances of amethod, antibody or antigen-binding fragment thereof, or use providedherein, the S. aureus infection is a bone or joint infection.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic showing that a range of animal models supports theuse of the combination of antibodies directed against alpha toxin (AT),clumping factor A (ClfA), and leukotoxins to achieve broad strain anddisease coverage.

FIG. 2 is a graph showing the efficacy of the combination of antibodiesdirected against AT, ClfA, and leukotoxins (MEDI6389) in inhibiting redblood cell (RBC) hemolysis as compared to the efficacy of an antibodydirected against AT (MEDI4893*) alone and the efficacy of a combinationof antibodies directed against ClfA (SAR114) and leukotoxins(SAN481-SYT*). (See Example 1.)

FIG. 3 is a graph showing the efficacy of the combination of antibodiesdirected against AT, ClfA, and leukotoxins (MEDI6389) in maintainingmonocyte viability as compared to the efficacy an antibody directedagainst leukotoxins (SAN481-SYT*) alone and the efficacy of acombination of antibodies directed against AT (MEDI4893*) and ClfA(SAR114). (See Example 1.)

FIG. 4 is a graph showing the efficacy of the combination of antibodiesdirected against AT, ClfA, and leukotoxins (MEDI6389) in inhibitingfibrinogen (Fg) binding as compared to the efficacy of an antibodydirected against ClfA (SAR114) alone and the efficacy of a combinationof antibodies directed against AT (MEDI4893*) and leukotoxins(SAN481-SYT*). (See Example 1.)

FIG. 5 provides a graph and images showing that the combination ofSAN481-SYT* and MEDI4893* is superior to the activity of eitherSAN481-SYT* or MEDI4893* alone in a dermonecrosis model with a S. aureuswound isolate. (See Example 2.)

FIG. 6 provides graphs showing that neutralization of AT, ClfA, andleukotoxins are necessary for protection in the rabbit bacteremia model.(See Example 3.)

FIG. 7 provides graphs comparing the efficacy of the combination ofantibodies directed against AT, ClfA, and leukotoxins (MEDI6389) againsttwo different bacterial bloodstream infections: HA-MRSA NRS382 (toppanel) and CA-MRSA SF8300 (bottom panel). (See Example 4).

FIG. 8 provides a graph and images showing that a mixed infection of S.aureus (SA), Pseudomonas aeruginosa (PA), and Streptococcus pyogenese(SP) resulted in delayed closure of skin lesions in a diabetic mousedermonecrosis model compared to an infection by SA alone. The imagesshow lesions at Day 43 post intra-dermal challenge. (See Example 5.)

FIG. 9 provides graphs and images showing that the combination ofantibodies directed against AT, ClfA, and leukotoxins (MEDI6389)improves the healing of wounds resulting from mixed-bacteria infections.(See Example 5).

FIG. 10 provides a sequence alignment of HIgB (SEQ ID NO:59), LukF (SEQID NO:60), and LukD (SEQ ID NO:61).

FIGS. 11A-G show that elevated glucose levels correlate with more severeS. aureus infections. (A and B) After infection with S. aureus, diabeticdb/db (A) and STZ (B) mice had increased mortality as compared tonon-diabetic controls. (C) After infection with S. aureus, diabeticdb/db mice had similar levels of S. aureus in their kidneys asnon-diabetic controls. (D) After infection with S. aureus, diabetic STZmice had similar levels of S. aureus in their kidneys as non-diabeticcontrols. (E, F, and G) Treatment with Rosiglitazone for 1 week prior toinfection with S. aureus reduced circulating glucose (E) and increasedsurvival (F), but did not affect the bacterial burden in the kidney (G).(See Example 7.)

FIGS. 12A-D show that systemic infection of the diabetic host lead to anAT-dependent increase in circulating NETs. (A) After infection with S.aureus, ELISA detected increased serum NETs in diabetic mice as comparedto non-diabetic controls. (B) Neutralization of S. aureus alpha toxin(AT) with the anti-alpha toxin monoclonal antibody MEDI4893*significantly reduced the number of NE-DNA complexes in the serum 48hours post-infection in diabetic mice. (C) After infection with S.aureus, Western blot showed increased citrinulated Histone H3 (H3cit) indiabetic mice as compared to non-diabetic controls. (D) Neutralizationof S. aureus AT increased survival of diabetic mice infected with S.aureus. (See Example 8.)

FIGS. 13A-D show that diabetic db/db mice have increased low densityneutrophils (LDNs). (A) After infection with S. aureus, the amount ofLDNs in the blood of infected diabetic db/db mice was significantlyincreased as compared to uninfected db/db mice or non-diabetic controls.(B) Treatment with Rosiglitazone for 1 week prior to infection with S.aureus reduced LDNs 48 hours post-infection. (C and D) Neutralization ofS. aureus AT prior to infection reduced LDNs (C) but did not affectoverall numbers of neutrophils (D) in diabetic db/db mice. (See Example9.)

FIG. 14 shows that, after infection with S. aureus, diabetic STZ micehad increased low density neutrophils LDNs. (See Example 9.)

FIG. 15A-D shows that delivery of a TGFβ neutralizing antibody prior toinfection is protective in diabetic mice (A) TGFβ significantlyincreased the number of LDNs in diabetic db/db blood, but not innon-diabetic control blood. (B and C) Delivery of a TGFβ neutralizingantibody provided prior to S. aureus infection reduced LDNs in blood(B), but did not affect the amount of bacteria in the kidney (C). (D)Delivery of a TGFβ neutralizing antibody provided prior to infectionincreased survival of diabetic db/db mice. (See Example 10.)

FIGS. 16A-E show that blocking the αVβ6/8 pathway prior to infection isprotective in diabetic mice. (A) β8 positive inflammatory monocytes anddendritic cells (DCs) increased in the livers of diabetic db/db mice,not C57BKS mice, following infection. (B) Integrin expression increasedon the surface of monocytes, and the overall number of DCs (not thedensity of β8 on DCs) increased. (C) Neutralizing αVβ6/8 prior toinfection decreased LDNs in the blood stream as compared toadministration of an anti-αVβ6 antibody or a control antibody (c-IgG).(D) Neutralizing αVβ6/8 prior to infection did not affect the amount ofbacteria in the kidney. (E) Neutralizing αVβ6/8 prior to infectionincreased survival as compared to administration of a control antibody(c-IgG). (See Example 10.)

FIGS. 17A-C show that AT influences activation of TGFβ independently ofαVβ8 expression on innate immune cells. (A) pSMAD levels were higher inthe livers of infected diabetic mice as compared with naïve diabeticmice and infected non-diabetic mice. (B) Neutralizing AT significantlyreduced pSMAD levels in the liver. (C) Neutralizing AT did not alter thenumbers of αVβ8 expressing innate immune cells. (See Example 11.)

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure provides combinations of antibodies andantigen-binding fragments thereof (e.g., monoclonal antibodies andantigen-binding fragments thereof) that bind to Staphylococcus aureus(S. aureus) alpha toxin (AT), clumping factor A (ClfA), and at least oneleukotoxin. The present disclosure also provides methods of using suchcombinations, for example, in the treatment or prevention of S. aureusinfections.

I. Definitions

As used herein, the term “alpha toxin” or “AT” refers to bacterial alphatoxin polypeptides including, but not limited to, native alpha toxinpolypeptides and isoforms of alpha toxin polypeptides. “Alpha toxin”encompasses full-length, unprocessed alpha toxin polypeptides as well asforms of alpha toxin polypeptides that result from processing within thecell. As used herein, the term “S. aureus alpha toxin” refers to apolypeptide comprising the amino acid sequence of

(SEQ ID NO: 57) adsdiniktgttdigsnttvktgdlvtydkengmhkkvfysfiddknhnkkllvirtkgtiagqyrvyseeganksglawpsaflcvqlqlpdnevaqisdyyprnsidtkeymstltygfngnvtgddtgkiggliganvsightlkyvqpdfktilesptdkkvgwkvifnnmvnqnwgpydrdswnpvygnqlfmktrngsmkaadnfldpnkassllssgfspdfatvitmdrkaskqqtnidviyervrddyqlhwtstnwkgtntkdkwtdrsserykidwekeemtn.The S. aureus alpha toxin  H35L mutant has the sequence (SEQ ID NO: 58)adsdiniktgttdigsnttvktgdlvtydkengmlkkvfysfiddknhnkkllvirtkgtiagqyrvyseeganksglawpsaflcvqlqlpdnevaqisdyyprnsidtkeymstltygfngnvtgddtgkiggliganvsightlkyvqpdfktilesptdkkvgwkvifnnmvnqnwgpydrdswnpvygnqlfmktrngsmkaadnfldpnkassllssgfspdfatvitmdrkaskqqtnidviyervrddyqlhwtstnwkgtntkdkwtdrsserykidwekeemtn.

A “alpha toxin polynucleotide,” “alpha toxin nucleotide,” or “alphatoxin nucleic acid” refer to a polynucleotide encoding alpha toxin.

As used herein, the term “clumping factor A” or “ClfA” refers tobacterial clumping factor A polypeptides including, but not limited to,native clumping factor A polypeptides and isoforms of clumping factor Apolypeptides. “Clumping factor A” encompasses full-length, unprocessedclumping factor A polypeptides as well as forms of clumping factor Apolypeptides that result from processing within the cell. A “clumpingfactor A polynucleotide,” “clumping factor A nucleotide,” or “clumpingfactor A nucleic acid” refer to a polynucleotide encoding alpha toxin.

As used herein, the term “leukotoxin” refers to bacterial leukotoxinpolypeptides including, but not limited to, native leukotoxinpolypeptides and isoforms of leukotoxin polypeptides. “Leukotoxin”encompasses a full-length, unprocessed leukotoxin polypeptides as wellas forms of leukotoxin polypeptides that result from processing withinthe cell. Leukotoxins include LukSF, leukotoxin ED (LukED), HlgAB,HlgCB), and leukotoxin AB (LukAB, also known as LukGH). As used herein,the term “S. aureus HIgB” refers to a polypeptide comprising the aminoacid sequence of SEQ ID NO:59. As used herein, the term “S. aureus LukF”refers to a polypeptide comprising the amino acid sequence of SEQ IDNO:60. As used herein, the term “S. aureus LukD” refers to a polypeptidecomprising the amino acid sequence of SEQ ID NO:61. As used herein, theterm “S. aureus HIgB” refers to a polypeptide comprising the amino acidsequence of SEQ ID NO:59. (See FIG. 10.) A “leukotoxin polynucleotide,”“leukotoxin nucleotide,” or “leukotoxin nucleic acid” refer to apolynucleotide encoding a leukotoxin.

The term “antibody” means an immunoglobulin molecule that recognizes andspecifically binds to a target, such as a protein, polypeptide, peptide,carbohydrate, polynucleotide, lipid, or combinations of the foregoingthrough at least one antigen recognition site within the variable regionof the immunoglobulin molecule. As used herein, the term “antibody”encompasses intact polyclonal antibodies, intact monoclonal antibodies,chimeric antibodies, humanized antibodies, human antibodies, fusionproteins comprising an antibody, and any other modified immunoglobulinmolecule so long as the antibodies exhibit the desired biologicalactivity. An antibody can be of any the five major classes ofimmunoglobulins: IgA, IgD, IgE, IgG, and IgM, or subclasses (isotypes)thereof (e.g. IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2), based on theidentity of their heavy-chain constant domains referred to as alpha,delta, epsilon, gamma, and mu, respectively. The different classes ofimmunoglobulins have different and well known subunit structures andthree-dimensional configurations. Antibodies can be naked or conjugatedto other molecules such as toxins, radioisotopes, etc.

The term “monoclonal antibodies,” as used herein, refers to antibodiesthat are produced by a single clone of B-cells and bind to the sameepitope. In contrast, the term “polyclonal antibodies” refers to apopulation of antibodies that are produced by different B-cells and bindto different epitopes of the same antigen.

The term “antibody fragment” refers to a portion of an intact antibody.An “antigen-binding fragment,” “antigen-binding domain,” or“antigen-binding region,” refers to a portion of an intact antibody thatbinds to an antigen. An antigen-binding fragment can contain theantigenic determining regions of an intact antibody (e.g., thecomplementarity determining regions (CDR)). Examples of antigen-bindingfragments of antibodies include, but are not limited to Fab, Fab′,F(ab′)2, and Fv fragments, linear antibodies, and single chainantibodies. An antigen-binding fragment of an antibody can be derivedfrom any animal species, such as rodents (e.g., mouse, rat, or hamster)and humans or can be artificially produced.

A whole antibody typically consists of four polypeptides: two identicalcopies of a heavy (H) chain polypeptide and two identical copies of alight (L) chain polypeptide. Each of the heavy chains contains oneN-terminal variable (VH) region and three C-terminal constant (CHI, CH2and CH3) regions, and each light chain contains one N-terminal variable(VL) region and one C-terminal constant (CL) region. The variableregions of each pair of light and heavy chains form the antigen bindingsite of an antibody. The VH and VL regions have the same generalstructure, with each region comprising four framework regions, whosesequences are relatively conserved. The term “framework region,” as usedherein, refers to the relatively conserved amino acid sequences withinthe variable region which are located between the hypervariable orcomplementary determining regions (CDRs). There are four frameworkregions in each variable domain, which are designated FR1, FR2, FR3, andFR4. The framework regions form the R sheets that provide the structuralframework of the variable region (see, e.g., C. A. Janeway et al.(eds.), Immunobiology, 5th Ed., Garland Publishing, New York, N.Y.(2001)). The three CDRs, known as CDR1, CDR2, and CDR3, form the“hypervariable region” of an antibody, which is responsible for antigenbinding.

The terms “VL” and “VL domain” are used interchangeably to refer to thelight chain variable region of an antibody.

The terms “VH” and “VH domain” are used interchangeably to refer to theheavy chain variable region of an antibody.

The term “Kabat numbering” and like terms are recognized in the art andrefer to a system of numbering amino acid residues in the heavy andlight chain variable regions of an antibody or an antigen-bindingfragment thereof. In certain aspects, CDRs can be determined accordingto the Kabat numbering system (see, e.g., Kabat E A & Wu T T (1971) AnnNY Acad Sci 190: 382-391 and Kabat E A et al., (1991) Sequences ofProteins of Immunological Interest, Fifth Edition, U.S. Department ofHealth and Human Services, NIH Publication No. 91-3242). Using the Kabatnumbering system, CDRs within an antibody heavy chain molecule aretypically present at amino acid positions 31 to 35, which optionally caninclude one or two additional amino acids, following 35 (referred to inthe Kabat numbering scheme as 35A and 35B) (CDR1), amino acid positions50 to 65 (CDR2), and amino acid positions 95 to 102 (CDR3). Using theKabat numbering system, CDRs within an antibody light chain molecule aretypically present at amino acid positions 24 to 34 (CDR1), amino acidpositions 50 to 56 (CDR2), and amino acid positions 89 to 97 (CDR3). Ina specific embodiment, the CDRs of the antibodies described herein havebeen determined according to the Kabat numbering scheme.

Chothia refers instead to the location of the structural loops (Chothiaand Lesk, J. Mol. Biol. 196:901-917 (1987)). The end of the ChothiaCDR-H1 loop when numbered using the Kabat numbering convention variesbetween H32 and H34 depending on the length of the loop (this is becausethe Kabat numbering scheme places the insertions at H35A and H35B; ifneither 35A nor 35B is present, the loop ends at 32; if only 35A ispresent, the loop ends at 33; if both 35A and 35B are present, the loopends at 34). The AbM hypervariable regions represent a compromisebetween the Kabat CDRs and Chothia structural loops, and are used byOxford Molecular's AbM antibody modeling software.

Loop Kabat AbM Chothia L1 L24-L34 L24-L34 L24-L34 L2 L50-L56 L50-L56L50-L56 L3 L89-L97 L89-L97 L89-L97 H1 H31-H35B H26-H35B H26-H32 . . . 34(Kabat Numbering) H1 H31-H35 H26-H35 H26-H32 (Chothia Numbering) H2H50-H65 H50-H58 H52-H56 H3 H95-H102 H95-H102 H95-H102

As used herein, the term “constant region” or “constant domain” areinterchangeable and have its meaning common in the art. The constantregion is an antibody portion, e.g., a carboxyl terminal portion of alight and/or heavy chain which is not directly involved in binding of anantibody to antigen but which can exhibit various effector functions,such as interaction with the Fc receptor. The constant region of animmunoglobulin molecule generally has a more conserved amino acidsequence relative to an immunoglobulin variable domain.

As used herein, the term “heavy chain” when used in reference to anantibody can refer to any distinct type, e.g., alpha (α), delta (δ),epsilon (ε), gamma (γ), and mu (μ), based on the amino acid sequence ofthe constant domain, which give rise to IgA, IgD, IgE, IgG, and IgMclasses of antibodies, respectively, including subclasses of IgG, e.g.,IgG₁, IgG₂, IgG₃, and IgG₄. Heavy chain amino acid sequences are wellknown in the art. In specific embodiments, the heavy chain is a humanheavy chain.

As used herein, the term “light chain” when used in reference to anantibody can refer to any distinct type, e.g., kappa (κ) or lambda (λ)based on the amino acid sequence of the constant domains. Light chainamino acid sequences are well known in the art. In specific embodiments,the light chain is a human light chain.

A “chimeric” antibody refers to an antibody or fragment thereofcomprising both human and non-human regions. A “humanized” antibody is aantibody comprising a human antibody scaffold and at least one CDRobtained or derived from a non-human antibody. Non-human antibodiesinclude antibodies isolated from any non-human animal, such as, forexample, a rodent (e.g., a mouse or rat). A humanized antibody cancomprise, one, two, or three CDRs obtained or derived from a non-humanantibody. A fully human antibody does not contain any amino acidresidues obtained or derived from a non-human animal. It will beappreciated that fully human and humanized antibodies carry a lower riskfor inducing immune responses in humans than mouse or chimericantibodies (see, e.g., Harding et al., mAbs, 2(3): 256-26 (2010)).

As used herein, an “epitope” is a term in the art and refers to alocalized region of an antigen to which an antibody or antigen-bindingfragment thereof can specifically bind. An epitope can be, for example,contiguous amino acids of a polypeptide (linear or contiguous epitope)or an epitope can, for example, come together from two or morenon-contiguous regions of a polypeptide or polypeptides (conformational,non-linear, discontinuous, or non-contiguous epitope). In certainembodiments, the epitope to which an antibody or antigen-bindingfragment thereof binds can be determined by, e.g., NMR spectroscopy,X-ray diffraction crystallography studies, ELISA assays,hydrogen/deuterium exchange coupled with mass spectrometry (e.g., liquidchromatography electrospray mass spectrometry), array-basedoligo-peptide scanning assays, and/or mutagenesis mapping (e.g.,site-directed mutagenesis mapping). For X-ray crystallography,crystallization can be accomplished using any of the known methods inthe art (e.g., Giegé R et al., (1994) Acta Crystallogr D BiolCrystallogr 50(Pt 4): 339-350; McPherson A (1990) Eur J Biochem 189:1-23; Chayen N E (1997) Structure 5: 1269-1274; McPherson A (1976) JBiol Chem 251: 6300-6303). Antibody/antigen-binding fragment thereof:antigen crystals can be studied using well known X-ray diffractiontechniques and can be refined using computer software such as X-PLOR(Yale University, 1992, distributed by Molecular Simulations, Inc.; see,e.g., Meth Enzymol (1985) volumes 114 & 115, eds Wyckoff H W et al.;U.S. 2004/0014194), and BUSTER (Bricogne G (1993) Acta Crystallogr DBiol Crystallogr 49(Pt 1): 37-60; Bricogne G (1997) Meth Enzymol 276A:361-423, ed Carter C W; Roversi P et al., (2000) Acta Crystallogr D BiolCrystallogr 56(Pt 10): 1316-1323). Mutagenesis mapping studies can beaccomplished using any method known to one of skill in the art. See,e.g., Champe M et al., (1995) J Biol Chem 270: 1388-1394 and CunninghamB C & Wells J A (1989) Science 244: 1081-1085 for a description ofmutagenesis techniques, including alanine scanning mutagenesistechniques.

An antibody that “binds to the same epitope” as a reference antibodyrefers to an antibody that binds to the same amino acid residues as thereference antibody. The ability of an antibody to bind to the sameepitope as a reference antibody can determined by a hydrogen/deuteriumexchange assay (see Coales et al. Rapid Commun. Mass Spectrom. 2009; 23:639-647) or x-ray crystallography.

As used herein, the terms “immunospecifically binds,”“immunospecifically recognizes,” “specifically binds,” and “specificallyrecognizes” are analogous terms in the context of antibodies orantigen-binding fragments thereof. These terms indicate that theantibody or antigen-binding fragment thereof binds to an epitope via itsantigen-binding domain and that the binding entails some complementaritybetween the antigen binding domain and the epitope. Accordingly, forexample, an antibody that “specifically binds” to a first S. aureusleukotoxin may also bind to other S. aureus leukotoxins, but the extentof binding to an un-related, non-leukotoxin protein is less than about10% of the binding of the antibody to the first S. aureus leukotoxin asmeasured, e.g., by a radioimmunoassay (RIA), enzyme-linked immunosorbentassay (ELISA), BiaCore or an octet binding assay.

An antibody is said to “competitively inhibit” binding of a referenceantibody to a given epitope if it preferentially binds to that epitopeor an overlapping epitope to the extent that it blocks, to some degree,binding of the reference antibody to the epitope. Competitive inhibitionmay be determined by any method known in the art, for example,competition ELISA assays. An antibody may be said to competitivelyinhibit binding of the reference antibody to a given epitope by at least90%, at least 80%, at least 70%, at least 60%, or at least 50%.

The term “nucleic acid sequence” is intended to encompass a polymer ofDNA or RNA, i.e., a polynucleotide, which can be single-stranded ordouble-stranded and which can contain non-natural or alterednucleotides. The terms “nucleic acid” and “polynucleotide” as usedherein refer to a polymeric form of nucleotides of any length, eitherribonucleotides (RNA) or deoxyribonucleotides (DNA). These terms referto the primary structure of the molecule, and thus include double- andsingle-stranded DNA, and double- and single-stranded RNA. The termsinclude, as equivalents, analogs of either RNA or DNA made fromnucleotide analogs and modified polynucleotides such as, though notlimited to, methylated and/or capped polynucleotides. Nucleic acids aretypically linked via phosphate bonds to form nucleic acid sequences orpolynucleotides, though many other linkages are known in the art (e.g.,phosphorothioates, boranophosphates, and the like).

An S. aureus infection can occur, for example, as a skin or soft tissueinfection (SSTI) or bacteremia. S. aureus bacteria can travel throughthe bloodstream and infect a site in the body, resulting in pneumonia,ICU pneumonia, a diabetic infection of the lower limbs, diabetic footulcer (DFU), a bone or joint infection, a device infection, a woundinfection, a surgical site infection, or osteomyelitis.

“Transfection,” “transformation,” or “transduction,” as used herein,refer to the introduction of one or more exogenous polynucleotides intoa host cell by using physical or chemical methods. Many transfectiontechniques are known in the art and include, for example, calciumphosphate DNA co-precipitation (see, e.g., Murray E. J. (ed.), Methodsin Molecular Biology, Vol. 7, Gene Transfer and Expression Protocols,Humana Press (1991)); DEAE-dextran; electroporation; cationicliposome-mediated transfection; tungsten particle-facilitatedmicroparticle bombardment (Johnston, Nature, 346: 776-777 (1990)); andstrontium phosphate DNA co-precipitation (Brash et al, Mol. Cell Biol.,7: 2031-2034 (1987)). Phage or viral vectors can be introduced into hostcells, after growth of infectious particles in suitable packaging cells,many of which are commercially available.

As used herein, the terms “treatment,” “treating,” and the like, referto obtaining a desired pharmacologic and/or physiologic effect. In oneembodiment, the effect is therapeutic, i.e., the effect partially orcompletely cures a disease and/or adverse symptom attributable to thedisease.

A “therapeutically effective amount” refers to an amount effective, atdosages and for periods of time necessary, to achieve a desiredtherapeutic result (e.g., treatment of S. aureus infection). Thetherapeutically effective amount may vary according to factors such asthe disease state, age, sex, and weight of the individual, and theability of the antibody or antigen-binding fragment to elicit a desiredresponse in the individual.

A “prophylactically effective amount” refers to an amount effective, atdosages and for periods of time necessary, to achieve a desiredprophylactic result (e.g., prevention of S. aureus infection or diseaseonset).

The terms “administer”, “administering”, “administration”, and the like,as used herein, refer to methods that may be used to enable delivery ofa drug, e.g., a combination of anti-S. aureus antibodies orantigen-binding fragments thereof to the desired site of biologicalaction (e.g., intravenous administration). Administration techniquesthat can be employed with the agents and methods described herein arefound in e.g., Goodman and Gilman, The Pharmacological Basis ofTherapeutics, current edition, Pergamon; and Remington's, PharmaceuticalSciences, current edition, Mack Publishing Co., Easton, Pa.

Administration “in combination with” one or more further therapeuticagents includes simultaneous (concurrent) or consecutive administrationin any order.

As used in the present disclosure and claims, the singular forms “a,”“an,” and “the” include plural forms unless the context clearly dictatesotherwise.

Unless specifically stated or obvious from context, as used herein, theterm “or” is understood to be inclusive. The term “and/or” as used in aphrase such as “A and/or B” herein is intended to include both “A andB,” “A or B,” “A,” and “B.” Likewise, the term “and/or” as used in aphrase such as “A, B, and/or C” is intended to encompass each of thefollowing embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C;A and C; A and B; B and C; A (alone); B (alone); and C (alone).

II. Anti-Staphylococcus aureus Antibodies and Combinations Thereof

As provided herein, antibodies and antigen-binding fragments thereof(e.g., monoclonal antibodies and fragments) that bind to S. aureusproteins can be used in combination. In particular, antibodies andantigen-binding fragments thereof that bind to S. aureus alpha toxin(AT) protein, antibodies and antigen-binding fragments thereof that bindto S. aureus clumping factor A (ClfA) protein, and antibodies anantigen-binding fragments thereof that bind to at least one S. aureusleukotoxin protein can advantageously be used in combination.

Alpha toxin (AT) is a key virulence factor in several S. aureusdiseases, including pneumonia, skin and soft tissue infections (SSTI),and bacteremia (Bubeck Wardenburg, J. and O. Schneewind, J. Exp. Med.,205: 287-294 (2008); Inoshima et al., J. Invest. Dermatol., 132:1513-1516 (2012); and Foletti et al., supra). Passive immunization withanti-AT monoclonal antibodies reduced disease severity in pneumonia anddermonecrosis models (Hua et al., Antimicrob. Agents Chemother., 58:1108-1117 (2014); Tkaczyk et al., Clin. Vaccine Immunol., 19: 377-385(2012); and Ragle, B. E. and J. Wardenburg Bubeck, Infect. Immun., 77:2712-2718 (2009)), and vaccination with an AT toxoid containing an H35Lmutation (ATH35L) protected against death in mouse lethal bacteremia andpneumonia models (Bubeck Wardenburg, supra, Foletti et al., supra, Huaet al., supra, Ragle, supra, Menzies, B. E. and D. S Kernodle, Infect.Immun., 77: 2712-2718 (2009); and Adhikari et al., PLoS One, 7: e38567(2012)). AT contributes to multiple aspects of S. aureus pathogenesisduring bacteremia and sepsis, including stimulating a hyperinflammatoryresponse characteristic of sepsis and activating ADAM10-mediatedcleavage of endothelial tight junctions, leading to a loss in vascularintegrity (Powers et al., J Infect. Dis., 206: 352-356 (2012); Wilke, G.A. and J. Bubeck Wardenburg, Proc. Natl. Acad. Sci. USA, 107:13473-13478 (2010); and Becker et al., J Innate Immun., 6: 619-631(2014)). AT also has been demonstrated to target platelets, whichprevents repair of the injured endothelial barrier and promotes organdysfunction through platelet-neutrophil aggregate formation (Powers etal., Cell Host Microbe, 17: 775-787 (2015)). Alpha toxin structure andfunction is described in detail in, for example, Bhakdi, S. and J.Tranum-Jensen, Microbiol. Mol. Biol. Rev., 55(4): 733-751 (1991).

Monoclonal and polyclonal antibodies that bind AT are known in the art(see, e.g., Hua et al., Antimicrob. Agents Chemother., 58(2): 1108-1117(2014); and Oganesyan et al., J. Biol. Chem., 289: 29874-29880 (2014))and are commercially available from sources such as, for example, SigmaAldrich (St. Louis, Mo.) and AbCam (Cambridge, Mass.). Exemplaryantibodies that bind to AT are disclosed, for example, in WO 2012/109285and WO 2014/074540 (both of which are herein incorporated by referencein their entireties).

In one instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to S. aureusalpha toxin (AT) comprises, consists essentially of, or consists of (i)a heavy chain polypeptide comprising a CDR1 amino acid sequence of SEQID NO:1, a CDR2 amino acid sequence of SEQ ID NO:2, and a CDR3 aminoacid sequence of SEQ ID NO:3, and (ii) a light chain polypeptidecomprising a CDR1 amino acid sequence of SEQ ID NO:10, a CDR2 amino acidsequence of SEQ ID NO:11, and a CDR3 amino acid sequence of SEQ IDNO:12. In another instance, the heavy chain polypeptide of an antibodyor antigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to S. aureus AT comprises, consists essentially of,or consists of a variable region amino acid sequence of SEQ ID NO:19. Inanother instance, the light chain polypeptide of an antibody orantigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to S. aureus AT comprises, consists essentially of,or consists of a variable region amino acid sequence of SEQ ID NO:33. Inanother instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to S. aureus ATcomprises, consists essentially of, or consists of a variable heavychain comprising, consisting essentially of, or consisting of the aminoacid sequence of SEQ ID NO:19 and a light chain variable regioncomprising, consisting essentially of, or consisting of the amino acidsequence of SEQ ID NO:33. In another instance, an antibody orantigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to S. aureus AT comprises, consists essentially of,or consists of a heavy chain comprising, consisting essentially of, orconsisting of the amino acid sequence of SEQ ID NO:47 and/or a lightchain variable region comprising, consisting essentially of, orconsisting of the amino acid sequence of SEQ ID NO:52.

Among the many S. aureus surface adhesins, clumping factor A (ClfA) hasbeen demonstrated to play an important role in serious bloodstreaminfections (Foster et al., Nat. Rev. Microbiol., 12: 49-62 (2014); andMurphy et al., Hum. Vaccin., 7(Suppl): 51-59 (2011)). ClfA bindsfibrinogen and facilitates both bacterial adherence to fibrinogen andbacterial clumping, both of which are key attributes in the developmentof an S. aureus bloodstream infection (Vaudaux et al., Infect. Immun.,63: 585-590 (1995); McDevitt et al., Mol. Microbiol., 11: 237-248(1994); and McDevitt et al., Eur. J. Biochem., 247: 416-424 (1997)).ClfA bound to fibrin or fibrinogen at a site of injury or coated on anindwelling device can facilitate bacterial colonization (Foster et al.,supra) and bacterial clumping, which is thought to enhance bacterialinvasiveness (McDevitt et al., Eur. J. Biochem., 247: 416-424 (1997);McAdow et al., PLoS Pathog., 7:e1002307 (2011); Flick et al., Blood,121: 1783-1794 (2013); and Rothfork et al., J. Immunol., 171: 5389-5395(2003)). ClfA also has been reported to impair complement depositionrequired for opsonophagocytic bacterial killing (OPK) (Hair et al.,Infect. Immun., 78: 1717-1727 (2010)). Consistent with theseobservations, isogenic ΔclfA mutants exhibited reduced virulence ininfection models (McAdow et al., supra; Josefsson et al., PLoS One, 3:e2206 (2008); and Josefsson et al., J Infect. Dis., 184: 1572-1580(2001)). In addition, passive immunization with human anti-ClfA-enrichedintravenous (i.v.) immunoglobulin (Ig) (INH-A21 or Veronate) or amonoclonal antibody (tefibazumab or Aurexis) improved disease outcomesfor patients with S. aureus bloodstream infections (Vernachio et al.,Antimcirob. Agents Chemother., 47: 3400-3406 (2003); and Vernachio etal., Antimicrob. Agents Chemother., 50: 511-518 (2006)). However, theseantibody preparations failed to improve outcomes in clinical studies ofprophylaxis or adjunctive therapy with vancomycin to prevent or treat S.aureus bacteremia in very-low-birth-weight infants (DeJonge et al., J.Pediatr., 151: 260-265 (2007); Capparelli et al., Antimicrob. AgentsChemother., 49: 4121-4127 (2005); and Bloom et al., Pediatr. Infect.Dis., 24: 858-866 (2005)). ClfA structure and function is described indetail in, for example, McDevitt et al., Mol. Microbiol., 11: 237-248(1994)).

Monoclonal and polyclonal antibodies which bind ClfA are known in theart (see, e.g., U.S. Pat. No. 7,364,738; Hall et al., Infect. Immun.,71(12): 6864-6870 (2003); and Vernachio et al., Antimicrob. AgentsChemother., 47(11): 3400-3406 (2003)) and are commercially availablefrom sources such as, for example, Creative Biolabs (Shirley, N.Y.).Exemplary antibodies that bind to ClfA are disclosed, for example, in WO2014/074540 and U.S. 62/702,762 (both of which are herein incorporatedby reference in their entireties).

In one instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to S. aureusclumping factor A (ClfA) comprises, consists essentially of, or consistsof (i) a heavy chain polypeptide comprising a CDR1 amino acid sequenceof SEQ ID NO:4, a CDR2 amino acid sequence of SEQ ID NO:5, and a CDR3amino acid sequence of SEQ ID NO:6, and (ii) a light chain polypeptidecomprising a CDR1 amino acid sequence of SEQ ID NO:13, a CDR2 amino acidsequence of SEQ ID NO:14, and a CDR3 amino acid sequence of SEQ IDNO:15. In another instance, the heavy chain polypeptide of an antibodyor antigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to S. aureus ClfA comprises, consists essentially of,or consists of a variable region amino acid sequence of SEQ ID NO:20. Inanother instance, the light chain polypeptide of an antibody orantigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to S. aureus ClfA comprises, consists essentially of,or consists of a variable region amino acid sequence of SEQ ID NO:34. Inanother instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to S. aureusClfA comprises, consists essentially of, or consists of a variable heavychain comprising, consisting essentially of, or consisting of the aminoacid sequence of SEQ ID NO:20 and a light chain variable regioncomprising, consisting essentially of, or consisting of the amino acidsequence of SEQ ID NO:34. In certain instances, an antibody orantigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to S. aureus ClfA comprises a heavy chain constantdomain comprising the amino acid sequence of CSYHLC (SEQ ID NO:55),MHEACSYHLCQKSLSLS (SEQ ID NO:56), or amino acids 233-454 of SEQ IDNO:49. In another instance, an antibody or antigen-binding fragment(e.g., monoclonal antibody or fragment) that specifically binds to S.aureus ClfA comprises, consists essentially of, or consists of a heavychain comprising, consisting essentially of, or consisting of the aminoacid sequence of SEQ ID NO:49 and/or a light chain variable regioncomprising, consisting essentially of, or consisting of the amino acidsequence of SEQ ID NO:53.

In another instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to S. aureusClfA (e.g., an antibody with the CDR, VH and/or VL, or heavy and orlight chains of SAR114-N3Y) has IC50's for ClfA001, ClfA002, and ClfA004in a fibrinogen binding inhibition assay that are within 2 μg/ml of eachother. For example, the IC₅₀'s of the antibody or antigen-bindingfragment thereof for ClfA001, ClfA002, and ClfA004 can all be between 1μg/ml and 5 μg/ml. The binding affinities (K_(D)) of the antibody orantigen-binding fragment thereof for ClfA001, ClfA002, and ClfA004 canall be all between 200 and 350 pM.

In another instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to S. aureusClfA (e.g., an antibody with the CDR, VH and/or VL, or heavy and orlight chains of SAR114-N3Y) has a monomeric purity that decreases by nomore than 5% after exposure to conventional white light at 2kLux/hr at23° C. for 14 days.

Leukotoxins are another type of S. aureus virulence factor. Leukotoxinstarget a broad range of immune cells for destruction. Leukotoxinsinclude Panton-Valentine leukocidin (LukSF-PV also known as LukSF),leukotoxin ED (LukED), gamma hemolysin (which exists as two toxins:HlgAB and HlgCB), and leukotoxin AB (LukAB, also known as LukGH). Incertain instances, an antibody or antigen-binding fragment thereof thatbinds to at least one leukotoxin binds to LukF, LukD, and/or HIgAB. Incertain instances, an antibody or antigen-binding fragment thereof thatbinds to at least one leukotoxin binds to LukF, LukD, and HIgB.

In one instance, an antibody or antigen-binding fragment (e.g.,monoclonal antibody or fragment) that specifically binds to at least oneS. aureus leukotoxin comprises, consists essentially of, or consists of(i) a heavy chain polypeptide comprising a CDR1 amino acid sequence ofSEQ ID NO:7, a CDR2 amino acid sequence of SEQ ID NO:8, and a CDR3 aminoacid sequence of SEQ ID NO:9, and (ii) a light chain polypeptidecomprising a CDR1 amino acid sequence of SEQ ID NO:16, a CDR2 amino acidsequence of SEQ ID NO:17, and a CDR3 amino acid sequence of SEQ IDNO:18. In another instance, the heavy chain polypeptide of an antibodyor antigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to at least one S. aureus leukotoxin comprises,consists essentially of, or consists of a variable region amino acidsequence of SEQ ID NO:32. In another instance, the light chainpolypeptide of an antibody or antigen-binding fragment (e.g., monoclonalantibody or fragment) that specifically binds to at least one S. aureusleukotoxin comprises, consists essentially of, or consists of a variableregion amino acid sequence of SEQ ID NO:46. In another instance, anantibody or antigen-binding fragment (e.g., monoclonal antibody orfragment) that specifically binds to at least one S. aureus leukotoxincomprises, consists essentially of, or consists of a variable heavychain comprising, consisting essentially of, or consisting of the aminoacid sequence of SEQ ID NO:32 and a light chain variable regioncomprising, consisting essentially of, or consisting of the amino acidsequence of SEQ ID NO:46. In another instance, an antibody orantigen-binding fragment (e.g., monoclonal antibody or fragment) thatspecifically binds to at least one S. aureus leukotoxin comprises,consists essentially of, or consists of a heavy chain comprising,consisting essentially of, or consisting of the amino acid sequence ofSEQ ID NO:50 and/or a light chain variable region comprising, consistingessentially of, or consisting of the amino acid sequence of SEQ IDNO:54.

Sequences of exemplary anti-AT, anti-ClFA, and anti-leukotoxinantibodies are provided below. Additional anti-AT antibodies areprovided, for example, in U.S. Pat. No. 9,527,905, which is hereinincorporated by reference in its entirety.) In certain instances, anantibody or antigen-binding fragment thereof described herein binds toAT, ClfA, or at lease one leukotoxin and comprises the six CDRs of anantibody listed in the two tables below (i.e., the three VH CDRs of theantibody listed in the first table and the three VL CDRs of the sameantibody listed in the second table).

The anti-AT antibody MEDI4893 is the half-life extended (YTE) version ofMEDI4893* or “LC10” described previously in International PatentApplication Publications WO 2012/109285 and WO 2014/074540 (both ofwhich are herein incorporated by reference in their entireties). Theanti-ClfA antibody SAR114-N3Y is described in U.S. ProvisionalApplication No. 62/702,762. The anti-leukotoxin antibody SAN481-SYT isthe half-life extended (YTE) version of SAN481-SYT*. SAN481-SYT* doesnot contain the YTE mutation.

VH CDR Amino Acid Sequences Antibody Antibody VH CDR1 VH CDR2 VH CDR3Name Target (SEQ ID NO:) (SEQ ID NO:) (SEQ ID NO:) MEDI4893 ATSHDMH (SEQ GIGTAGDTYYPD DRYSPTGHYYGMDV and ID NO: 1) SVKG (SEQ ID(SEQ ID NO: 3) MEDI4893* NO: 2) SAR114 ClfA NSYWS (SEQ YLYSSGRTNYTPSTHLGGFHYGGGFWF and ID NO: 4) LKS (SEQ ID DP (SEQ ID NO: 6) SAR114-NO: 5) N3Y 11H10 ClfA SFAMS (SEQ AISGSGGNTYYA IAFDI  ID NO: 62)DSVKG (SEQ ID (SEQ ID NO: 64) NO: 63) SAN481-SYT and Leuko- TYAMH (SEQVTSFDGSNEYYID DEYTGGWYSVGY SAN481- toxin ID NO: 7) SVKG (SEQ ID(SEQ ID NO: 9) SYT* NO: 8)

VL CDR Amino Acid Sequences Antibody VL CDR1 VL CDR2 VL CDR3 AntibodyTarget (SEQ ID NO:) (SEQ ID NO:) (SEQ ID NO:) MEDI4893 AT RASQSISSWLAKASSLES (SEQ ID KQYADYWT and (SEQ ID NO: 10) NO: 11) (SEQ ID NO: 12)MEDI4893* SAR114 ClfA RASQSITSYLN ASSSLQS (SEQ ID QESYSTPPT (SEQ and(SEQ ID NO: 13) NO: 14) ID NO 15) SAR114- N3Y 11H10 ClfA RASQGIRNDLVASSLQS (SEQ ID LQHNSYPFT (SEQ G (SEQ ID NO: 66) ID NO: 67) NO: 65)SAN481-SYT and Leuko- SGSSYNIGSNY RSIQRPS (SEQ ID AAWDDSLRAWV SAN481-toxin VY (SEQ ID  NO: 17) (SEQ ID NO: 18) SYT * NO: 16)

In certain instances, an antibody or antigen-binding fragment thereofdescribed herein binds to AT, ClfA, or at least one leukotoxin andcomprises the VH of an antibody listed in the following table, e.g., incombination with a VL.

Variable Heavy Chain (VH) Amino Acid Sequence Antibody Antibody TargetVH Amino Acid Sequence (SEQ ID NO) MEDI4893 ATEVQLVESGGGLVQPGGSLRLSCAASGFTFSSHDIVIEIWVRQA andTGKGLEWVSGIGTAGDTYYPDSVKGRFTISRENAKNSLYLQ MEDI4893*MNSLRAGDTAVYYCARDRYSPTGHYYGMDVWGQGTTVT VSS (SEQ ID NO: 19) SAR114 ClfAQVQLQESGPGLVKPSETLSLTCTVSGGSIQNSYWSWIRQPPG andKGLEWIGYLYSSGRTNYTPSLKSRVTISVDTSKNQFSLKLSS SAR114-VTAADTAVYYCARTHLGGFHYGGGFWFDPWGQGTLVTVS N3Y S (SEQ ID NO: 20) 11H10 ClfAEVQLLESGGGLVQPGGSLRLSCAASGFTFSSFAMSWVRQAPGKGLEWVSAISGSGGNTYYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAKIAFDIWGQGTMVT VSS (SEQ ID NO: 68) SAR72 ClfAEVQLVESGGGLVKPGGSLRVSCAASGFSFRNALMSWVRQAPGKGLEWVGRSKTDGGTTDYAAPVKGRFTISRDDSKNTLYLQMNSLKTEDTAVYYCTTGPGGGPPGDYYYDGMDVWGQG TTVTVSS (SEQ ID NO: 21) SAR80ClfA EVQLVESGGDLVKPGGSLRLSCAASGFTFSDAWMTWVRQAPGKGLEWVGRIRSKTAGGTTDYAAPVKGRFTISRDDSKNTLYLQMTSLKIEDTALYYCMTDGLGLLNFGDSDPHEYWGQGT RVTVSS (SEQ ID NO: 22) SAR113ClfA EVQLVQSGAEVKKPGESLKISCKAXGYXFTSYWIGWVRQVPGKGLEWMGIIYPGDSDTRHSPSFQGQVTISVDKSISTAYLQWSSLKASDSAMYYCARHQSGSHGFDAFEIWGQGTMVTVSS (SEQ ID NO: 23) SAR132 ClfAEVQLVQSGAEVKKPGESLKISCKGSGYNFTNYWIAWVRQMPGKGLEWMGIIYSGDSDTRYSPSFLGQVSISVDKSFTTAYLQWRSLKASDTAMYYCARRPGGQKPYDYWGQGTLVTVSS (SEQ ID NO: 24) SAR352 ClfAEVQLVESGGGLVKPGGSLRLSCAASGFTFNNAWMSWVRQAPGKGLEWVGRIKSETAGGTTDYAAPVKGRFSISRDDSRNTLYLEMNSLKTEDTAVYYCTTDSYTPLEEPCPNGVCYTYYYY GMDVWGQGTTVTVSS (SEQ ID NO: 25)SAR372 ClfA EVQLVESGGGLVQPGGSLRLSCAASGFIFNRYSMNWVRQAPGKGLEWVSYISSSSSPIYYADSVKGRFTISRDNAKNSLYLQMNSLRDEDTAVYYCASRVTLGLEFDFWGQGTLVTVSS (SEQ ID NO: 26) SAR510 ClfAQVTLRESGPALVKPTQTLTLTCTFSGFSLSTSGMCVGWIRQPPGKALEWLALIEWDDDKYYNTSLKTRLSISKDTSKNQVVLTMTNMDPVDTGTYYCARHSSSSRGFDYWGQGALVTVSS (SEQ ID NO: 27) SAR547 ClfAEVQLVQSGAEVKKPGESLKISCKGSGYSFTTYWIAWVRQMPGKGLEWMGIIYPGDSDTRYSPSFQGQVTISADKSTATAYLQWSSLNASDSAMYYCARQGGSHGYDAFHMWGQGTMVTVS S (SEQ ID NO: 28) SAS1 ClfAEVQLLESGGGLVQPGGSLRLSCTASGFTFSTYALNWVRQAPGKGLEWVAGINGTGYNTYYADSVRGRFTISRDNSKNTVTLEMNSLRVEDTATYYCHKVPWWGQGTLVSVSS (SEQ ID NO: 29) SAS19 ClfAQVQLQESGPRLVKPSETLSLTCFVSGGSINNSYWTWIRQPPGQGLEWIGFVFSSGRTNYSPSLKSRVTISVDTSKNLFSLRLTSVTAADTAVYFCARQVHYDFWSGYSLTKTNWFDPWGQGTLV TVSS (SEQ ID NO: 30) SAS203 ClfAQVQLQESGPGLVKPSETLSLTCVVSGGSINNSYWTWIRQPPGQGLEWIGFVYSSGRTYYSPSLKSRVTISVDTSKNFFSLRLNSVTAADTAVYFCARQVHYDLWSGYSLTKTNWFDPWGQGTL VTVSS (SEQ ID NO: 31) SAN481-Leuko- QLQLVESGGGAVQPGRSLKLSCAASGFTFSTYAMHWVRQA SYT and toxinPGRGLEWVAVTSFDGSNEYYIDSVKGRFTISRDNTKNTLYL SAN481-QMTGLRVEDTALYFCARDEYTGGWYSVGYWGQGTLVTVS SYT* S (SEQ ID NO: 32)

In certain instances, an antibody or antigen-binding fragment thereofdescribed herein binds to AT, ClfA, or at least one leukotoxin andcomprises the VL of an antibody listed in the following table, e.g., incombination with a VH, optionally the VH of the same antibody listed inthe preceding table.

Variable Light Chain (VL) Amino Acid Sequence Antibody Antibody TargetVL Amino Acid Sequence (SEQ ID NO) MEDI4893 ATDIQMTQSPSTLSASVGDRVTITCRASQSISSWLAWYQQKPG andKAPKLLIYKASSLESGVPSRFSGSGSGTEFTLTISSLQPDDFAT MEDI4893*YYCKQYADYWTFGQGTKVEIK (SEQ ID NO: 33) SAR114 ClfADIQMTQSPSSLSASVGDRVTITCRASQSITSYLNWYQQKPGK andAPKLLIYASSSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATY SAR114-YCQESYSTPPTFGQGTKVEIK (SEQ ID NO: 34) N3Y 11H10 ClfADIQMTQSPSSLSASVGDRVTITCRASQGIRNDLGWYQQKPGKAPKRLIYVASSLQSGVPSRFSGSGSGTEFTLTISSLQPEDFATYYCLQHNSYPFTFGPGTKVDIK (SEQ ID NO: 69) SAR72 ClfASYELTQPPSVSVSPGQTARITCSGDAVPKKYAYWYQQKSGQAPVLVIYEDKKRPSGIPERFSGSSSGTMATLTISGAQVEDEADYYCYSTDSSEGVFGGGTKLTVL (SEQ ID NO: 35) SAR80 ClfASYELTQPPSVSVSPGQTARITCSGDALPKKYAYWYQQKSGQAPVLVIHEDTKRPSGIPERFSGSSSGTMATLTISGAQVEDEADYHCYSTDSSGVVFGGGTKLTVL (SEQ ID NO: 36) SAR113 ClfADIVLTQSPDSLAVSLGERATINCKSSQGVLSRSNNKNYLAWYQQKPGQPPKLLIYWASTRESGVPDRFSGSGSGTDFTLTISSLQAEDVAVYYCQQYYNNLRTFGQGTKVEIR (SEQ ID NO: 37) SAR132 ClfADIQMTQSPSTLSASVGDRVTITCRASQRISNWLAWYQKKPGKAPKLLIYKASTLESEVPSRFSGSGSGTEFTLTISSLQPDDLATYYCHQYISYYTFGQGTKLEIK (SEQ ID NO: 38) SAR352 ClfAQSVLTQPPSVSAAPGEKVTISCSGSSSNIGANSVSWYQQFPGTAPKLLIYDNDKRPSGVPDRFSGSKSGTSATLGITGLQTGDEADYYCGTWVGILSAGWVFGGGTKLTVL (SEQ ID NO: 39) SAR372 ClfAEIVLTQSPATLSLSPGERATLSCRASQSVSSNLAWYQQKPGQAPRLLIYDASNRATGIPDRFSGSGSGTDFTLTISSLKPEDFAVYYCQLRSNWAYTFGQGTKLEIK (SEQ ID NO: 40) SAR510 ClfASYGLTQPPSVSVSPGQTARITCSGDALAKQYVYWYQQKPGQAPVLVIDKDRERPSGIPERFSGSSSGTTVTLTISGVQAEDEADYYCQSADSSRTYVFGTGTKVTVL (SEQ ID NO: 41) SAR547 ClfADVVMTQSPLSLPVTLGQPASISCRSSQSLVHSDGNTYLNWFQQRPGQSPRRLIYKVSNRDSGVPDRFSGSGSGTDFTLKISRVEAEDVGVYYCMQGTHLTWTFGQGTKVEIK (SEQ ID NO: 42) SAS1 ClfADIVLTQSPESLAVSLGERATISCKSSQSLFFKSNNKNYLAWYQQKPGQPPKVIIYWASTRESGVPARFSGSGSGTDFTLTISSLQAEDVAVYFCHQYYSTQYSFGQGTKLEIK (SEQ ID NO: 43) SAS19 ClfADIQMTQSPSSLSASVGDTVTITCRTSQSISNFLNWYQQKPGKAPKLLIYAASSLQSGVPSRVNGSTSGTEFTLTLSSLQPEDFATYYCQQSYSTPWTFGQGTKVEIK (SEQ ID NO: 44) SAS203 ClfADIQMTQSPSSLSASVGDTVTITCRTSQSISNFLNWYQQKPGKAPKLLIYAASSLQSGVPSRFNGSTSGTDFTLTLSSLQPEDFATYYCQQSYSTPWTFGQGTKVEIK (SEQ ID NO: 45) SAN481- Leuko-QSVLTQPPSASGTPGQRVTISCSGSSYNIGSNYVYWYQQFPG SYT and toxinTAPKLLISRSIQRPSGVPDRFSGSKSVTSASLAISGLRSEDEAD SAN481-YYCAAWDDSLRAWVFGGGTKLTVL (SEQ ID NO: 46) SYT*

In certain instances, an antibody or antigen-binding fragment thereofdescribed herein binds to AT, ClfA, or at least one leukotoxin andcomprises the heavy chain of an antibody listed in the following table,e.g., in combination with a light chain.

Full-length heavy chain amino acid sequences AntibodyFull-Length Heavy Chain Amino Acid Sequence (SEQ ID Antibody Target NO)MEDI4893 AT EVQLVESGGGLVQPGGSLRLSCAASGFTFSSHDMIEIWVRQATGKGLEWVSGIGTAGDTYYPDSVKGRFTISRENAKNSLYLQMNSLRAGDTAVYYCARDRYSPTGHYYGMDVWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLYITREPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYT QKSLSLSPGK (SEQ ID NO: 47)MEDI4893* AT EVQLVESGGGLVQPGGSLRLSCAASGFTFSSHDMIEIWVRQATGKGLEWVSGIGTAGDTYYPDSVKGRFTISRENAKNSLYLQMNSLRAGDTAVYYCARDRYSPTGHYYGMDVWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDK SRWQQGNVFSCSVMHEALHNHYTQKSLS LSPGK (SEQ ID NO: 48) SAR114-ClfA QVQLQESGPGLVKPSETLSLTCTVSGGSIQNSYWSWIRQPPG N3YKGLEWIGYLYSSGRTNYTPSLKSRVTISVDTSKNQFSLKLSSVTAADTAVYYCARTHLGGFHYGGGFWFDPWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEACSYHLCQKSLSLSP GK (SEQ ID NO: 49) SAR114 ClfAQVQLQESGPGLVKPSETLSLTCTVSGGSIQNSYWSWIRQPPGKGLEWIGYLYSSGRTNYTPSLKSRVTISVDTSKNQFSLKLSSVTAADTAVYYCARTHLGGFHYGGGFWFDPWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSP GK (SEQ ID NO: 70) SAN481-Leuko- QLQLVESGGGAVQPGRSLKLSCAASGFTFSTYAMIHWVRQA SYT toxinPGRGLEWVAVTSFDGSNEYYIDSVKGRFTISRDNTKNTLYLQMTGLRVEDTALYFCARDEYTGGWYSVGYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLYITREPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSP GK (SEQ ID NO: 50) SAN481-Leuko- QLQLVESGGGAVQPGRSLKLSCAASGFTFSTYAMIHWVRQA SYT* toxinPGRGLEWVAVTSFDGSNEYYIDSVKGRFTISRDNTKNTLYLQMTGLRVEDTALYFCARDEYTGGWYSVGYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSP GK (SEQ ID NO: 51)

In certain instances, an antibody or antigen-binding fragment thereofdescribed herein binds to AT, ClfA, or at least one leukotoxin andcomprises the light chain of an antibody listed in the following table,e.g., in combination with a heavy chain, optionally the heavy chain ofthe same antibody listed in the preceding table.

Full-length light chain amino acid sequences AntibodyFull-Length Light Chain Amino Acid Sequence  Antibody Target (SEQ ID NO)MEDI4893 AT DIQMTQSPSTLSASVGDRVTITCRASQSISSWLAWYQQK andPGKAPKLLIYKASSLESGVPSRFSGSGSGTEFTLTISSLQP MEDI4893*DDFATYYCKQYADYWTFGQGTKVEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGE (SEQ ID NO: 52) SAR114- ClfADIQMTQSPSSLSASVGDRVTITCRASQSITSYLNWYQQK N3YPGKAPKLLIYASSSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQESYSTPPTFGQGTKVEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC (SEQ ID NO: 53) SAN481- Leuko-QSVLTQPPSASGTPGQRVTISCSGSSYNIGSNYVYWYQQ SYT and toxinFPGTAPKLLISRSIQRPSGVPDRFSGSKSVTSASLAISGLR SAN481-SEDEADYYCAAWDDSLRAWVFGGGTKLTVLGQPKAA SYT*PSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVAPTECS (SEQ ID NO: 54)

In certain aspects, the CDRs of an antibody or antigen-binding fragmentthereof can be determined according to the Chothia numbering scheme,which refers to the location of immunoglobulin structural loops (see,e.g., Chothia C & Lesk A M, (1987), J Mol Biol 196: 901-917; Al-LazikaniB et al., (1997) J Mol Biol 273: 927-948; Chothia C et al., (1992) J MolBiol 227: 799-817; Tramontano A et al., (1990) J Mol Biol 215(1):175-82; and U.S. Pat. No. 7,709,226). Typically, when using the Kabatnumbering convention, the Chothia CDR-H1 loop is present at heavy chainamino acids 26 to 32, 33, or 34, the Chothia CDR-H2 loop is present atheavy chain amino acids 52 to 56, and the Chothia CDR-H3 loop is presentat heavy chain amino acids 95 to 102, while the Chothia CDR-L1 loop ispresent at light chain amino acids 24 to 34, the Chothia CDR-L2 loop ispresent at light chain amino acids 50 to 56, and the Chothia CDR-L3 loopis present at light chain amino acids 89 to 97. The end of the ChothiaCDR-H1 loop when numbered using the Kabat numbering convention variesbetween H32 and H34 depending on the length of the loop (this is becausethe Kabat numbering scheme places the insertions at H35A and H35B; ifneither 35A nor 35B is present, the loop ends at 32; if only 35A ispresent, the loop ends at 33; if both 35A and 35B are present, the loopends at 34).

In certain aspects, provided herein are combinations of antibodies andantigen-binding fragments thereof that comprise the Chothia VH and VLCDRs of the MEDI4893, SAR114-N3Y, and/or SAN481-SYT antibodies. Incertain embodiments, antibodies or antigen-binding fragments thereofcomprise one or more CDRs, in which the Chothia and Kabat CDRs have thesame amino acid sequence. In certain embodiments, provided herein areantibodies and antigen-binding fragments thereof comprise combinationsof Kabat CDRs and Chothia CDRs.

In certain aspects, the CDRs of an antibody or antigen-binding fragmentthereof can be determined according to the IMGT numbering system asdescribed in Lefranc M-P, (1999) The Immunologist 7: 132-136 and LefrancM-P et al., (1999) Nucleic Acids Res 27: 209-212. According to the IMGTnumbering scheme, VH-CDR1 is at positions 26 to 35, VH-CDR2 is atpositions 51 to 57, VH-CDR3 is at positions 93 to 102, VL-CDR1 is atpositions 27 to 32, VL-CDR2 is at positions 50 to 52, and VL-CDR3 is atpositions 89 to 97. In a particular embodiment, provided herein arecombinations of antibodies and antigen-binding fragments thereof thatcomprise the IMGT VH and VL CDRs of MEDI4893, SAR114-N3Y, and/orSAN481-SYT antibodies, for example, as described in Lefranc M-P (1999)supra and Lefranc M-P et al., (1999) supra).

In certain aspects, the CDRs of an antibody or antigen-binding fragmentthereof can be determined according to MacCallum R M et al., (1996) JMol Biol 262: 732-745. See also, e.g., Martin A. “Protein Sequence andStructure Analysis of Antibody Variable Domains,” in AntibodyEngineering, Kontermann and Dubel, eds., Chapter 31, pp. 422-439,Springer-Verlag, Berlin (2001). In a particular embodiment, providedherein are combinations of antibodies or antigen-binding fragmentsthereof comprise the VH and VL CDRs of the MEDI4893, SAR114-N3Y, and/orSAN481-SYT antibodies determined by the method in MacCallum R M et al.

In certain aspects, the CDRs of an antibody or antigen-binding fragmentthereof can be determined according to the AbM numbering scheme, whichrefers AbM hypervariable regions which represent a compromise betweenthe Kabat CDRs and Chothia structural loops, and are used by OxfordMolecular's AbM antibody modeling software (Oxford Molecular Group,Inc.). In a particular embodiment, provided herein are combinations ofantibodies or antigen-binding fragments that and comprise VH and VL CDRsof the MEDI4893, SAR114-N3Y, and/or SAN481-SYT antibodies as determinedby the AbM numbering scheme.

In another aspect, the antibody or antigen-binding fragment thereof(e.g., monoclonal antibody or fragment) described herein can comprise aconstant region (Fc) of any suitable class (e.g., IgG, IgA, IgD, IgM,and IgE) that has been modified in order to improve the half-life of theantibody or antigen-binding fragment (e.g., monoclonal antibody orfragment). For example, the antibody or antigen-binding fragment thereof(e.g., monoclonal antibody or fragment) described herein can comprise anFc that comprises a mutation that extends half-life relative to the sameantibody without the mutation.

Fc region engineering is widely used in the art to extend the half-lifeof therapeutic antibodies and protect from degradation in vivo. In someembodiments, the Fc region of an IgG antibody or antigen-bindingfragment can be modified in order to increase the affinity of the IgGmolecule for the Fc Receptor-neonate (FcRn), which mediates IgGcatabolism and protects IgG molecules from degradation. Suitable Fcregion amino acid substitutions or modifications are known in the artand include, for example, the triple substitution M252Y/S254T/T256E(referred to as “YTE”) (see, e.g., U.S. Pat. No. 7,658,921; U.S. PatentApplication Publication 2014/0302058; and Yu et al., Antimicrob. AgentsChemother., 61(1): e01020-16 (2017)). In certain aspects, an antibody orantigen-binding binding fragment (e.g., monoclonal antibody or fragment)that binds to S. aureus AT comprises an Fc region comprising the YTEmutation. In certain aspects, an antibody or antigen-binding bindingfragment (e.g., monoclonal antibody or fragment) that binds to at leastone S. aureus leukotoxin comprises an Fc region comprising the YTEmutation. In certain aspects, an antibody or antigen-binding bindingfragment (e.g., monoclonal antibody or fragment) that binds to S. aureusAT comprises an Fc region comprising the YTE mutation and an antibody orantigen-binding binding fragment (e.g., monoclonal antibody or fragment)that binds to at least one S. aureus leukotoxin comprises an Fc regioncomprising the YTE mutation.

In another aspect, the Fc region can comprise the sequence CSYHLC(referred to as “N3Y”; SEQ ID NO:55). In certain aspects, an antibody orantigen-binding binding fragment (e.g., monoclonal antibody or fragment)that binds to S. aureus ClfA comprises an Fc region comprising the N3YFc variant.

In another aspect, the antibody or antigen-binding fragment thereof(e.g., monoclonal antibody or fragment) described herein can comprise aconstant region (Fc) of any suitable class (IgG, IgA, IgD, IgM, and IgE)that has been modified in order to improve effector functions (e.g.,opsonophagocytic bacterial killing (OPK)), optionally wherein thehalf-life of the antibody or antigen-binding fragment (e.g., monoclonalantibody or fragment) is also improved. For example, the antibody orantigen-binding fragment thereof (e.g., monoclonal antibody or fragment)described herein may comprise an Fc that comprises a mutation thatextends half-life relative to the same antibody without the mutation,and wherein the mutation does not inhibit OPK activity relative to thesame antibody or antigen-binding fragment the mutation. The N3Y Fcvariant, in particular, exhibits enhanced pharmacokinetic (PK)properties (e.g., serum persistence) and effector functions (e.g.,opsonophagocytic bacterial killing (OPK)) in certain antibodies ascompared to the YTE variants.

An antibody or antigen-binding fragment (e.g. monoclonal antibody orfragment) described herein can be, or can be obtained from, a humanantibody, a humanized antibody, a non-human antibody, or a chimericantibody. In one aspect, an antibody described herein, orantigen-binding fragment thereof, is a fully human antibody.

A human antibody, a non-human antibody, a chimeric antibody, or ahumanized antibody can be obtained by any means, including via in vitrosources (e.g., a hybridoma or a cell line producing an antibodyrecombinantly) and in vivo sources (e.g., rodents, human tonsils).Methods for generating antibodies are known in the art and are describedin, for example, Köhler and Milstein, Eur. J. Immunol., 5: 511-519(1976); Harlow and Lane (eds.), Antibodies: A Laboratory Manual, CSHPress (1988); and Janeway et al. (eds.), Immunobiology, 5th Ed., GarlandPublishing, New York, N.Y. (2001)). In certain embodiments, a humanantibody or a chimeric antibody can be generated using a transgenicanimal (e.g., a mouse) wherein one or more endogenous immunoglobulingenes are replaced with one or more human immunoglobulin genes. Examplesof transgenic mice wherein endogenous antibody genes are effectivelyreplaced with human antibody genes include, but are not limited to, theMedarex HUMAB-MOUSE™, the Kirin TC MOUSE™, and the Kyowa Kirin KM-MOUSE™(see, e.g., Lonberg, Nat. Biotechnol., 23(9): 1117-25 (2005), andLonberg, Handb. Exp. Pharmacol., 181: 69-97 (2008)). A humanizedantibody can be generated using any suitable method known in the art(see, e.g., An, Z. (ed.), Therapeutic Monoclonal Antibodies: From Benchto Clinic, John Wiley & Sons, Inc., Hoboken, N.J. (2009)), including,e.g., grafting of non-human CDRs onto a human antibody scaffold (see,e.g., Kashmiri et al., Methods, 36(1): 25-34 (2005); and Hou et al., J.Biochem., 144(1): 115-120 (2008)). In one embodiment, a humanizedantibody can be produced using the methods described in, e.g., U.S.Patent Application Publication 2011/0287485 A1.

III. Nucleic Acids, Vectors, and Host Cells

Also provided herein are one or more isolated nucleic acid sequencesthat encode the antibody or antigen-binding fragment thereof that bindsto AT, the antibody or antigen-binding fragment thereof that binds toClfA, or the antibody or antigen-binding fragment thereof that binds toat least one leukotoxin (optionally wherein one or more of theantibodies or antigen-binding fragments thereof is a monoclonal antibodyor fragment).

The disclosure further provides one or more vectors comprising one ormore nucleic acid sequences encoding antibody or antigen-bindingfragment thereof that binds to AT, the antibody or antigen-bindingfragment thereof that binds to ClfA, and/or the antibody orantigen-binding fragment thereof that binds to at least one leukotoxin(optionally wherein one or more of the antibodies or antigen-bindingfragments thereof is a monoclonal antibody or fragment). The vector canbe, for example, a plasmid, episome, cosmid, viral vector (e.g.,retroviral or adenoviral), or phage. Suitable vectors and methods ofvector preparation are well known in the art (see, e.g., Sambrook etal., Molecular Cloning, a Laboratory Manual, 3rd edition, Cold SpringHarbor Press, Cold Spring Harbor, N.Y. (2001), and Ausubel et al.,Current Protocols in Molecular Biology, Greene Publishing Associates andJohn Wiley & Sons, New York, N.Y. (1994)).

In addition to the nucleic acid sequence encoding the antibody orantigen-binding fragment thereof that binds to AT, the antibody orantigen-binding fragment thereof that binds to ClfA, and/or the antibodyor antigen-binding fragment thereof that binds to at least oneleukotoxin (optionally wherein one or more of the antibodies orantigen-binding fragments thereof is a monoclonal antibody or fragment),the vector desirably comprises expression control sequences, such aspromoters, enhancers, polyadenylation signals, transcriptionterminators, internal ribosome entry sites (IRES), and the like, thatprovide for the expression of the coding sequence in a host cell.Exemplary expression control sequences are known in the art anddescribed in, for example, Goeddel, Gene Expression Technology: Methodsin Enzymology, Vol. 185, Academic Press, San Diego, Calif. (1990).

The vector(s) comprising the nucleic acid(s) encoding the antibody orantigen-binding fragment thereof that binds to AT, the antibody orantigen-binding fragment thereof that binds to ClfA, or the antibody orantigen-binding fragment thereof that binds to at least one leukotoxin(optionally wherein one or more of the antibodies or antigen-bindingfragments thereof is a monoclonal antibody or fragment) can beintroduced into a host cell that is capable of expressing thepolypeptides encoded thereby, including any suitable prokaryotic oreukaryotic cell. As such, the present disclosure provides an isolatedcell comprising the vector. Host cells that may be used include thosethat can be easily and reliably grown, have reasonably fast growthrates, have well characterized expression systems, and can betransformed or transfected easily and efficiently. Examples of suitableprokaryotic cells include, but are not limited to, cells from the generaBacillus (such as Bacillus subtilis and Bacillus brevis), Escherichia(such as E. coli), Pseudomonas, Streptomyces, Salmonella, and Erwinia.Particularly useful prokaryotic cells include the various strains ofEscherichia coli (e.g., K12, HB101 (ATCC No. 33694), DH5a, DH10, MC1061(ATCC No. 53338), and CC102). Suitable eukaryotic cells are known in theart and include, for example, yeast cells, insect cells, and mammaliancells. In one embodiment, the vector is expressed in mammalian cells. Anumber of suitable mammalian host cells are known in the art, and manyare available from the American Type Culture Collection (ATCC, Manassas,Va.). Examples of suitable mammalian cells include, but are not limitedto, Chinese hamster ovary cells (CHO) (ATCC No. CCL61), CHO DHFR− cells(Urlaub et al, Proc. Natl. Acad. Sci. USA, 97: 4216-4220 (1980)), humanembryonic kidney (HEK) 293 or 293T cells (ATCC No. CRL1573), and 3T3cells (ATCC No. CCL92). Other suitable mammalian cell lines are themonkey COS-1 (ATCC No. CRL1650) and COS-7 cell lines (ATCC No. CRL1651),as well as the CV-1 cell line (ATCC No. CCL70). The mammalian celldesirably is a human cell. For example, the mammalian cell can be ahuman lymphoid or lymphoid derived cell line, such as a cell line ofpre-B lymphocyte origin, a PER.C6® cell line (Crucell Holland B.V., TheNetherlands), or human embryonic kidney (HEK) 293 or 293T cells (ATCCNo. CRL1573).

A nucleic acid sequence encoding amino acids of any of the antibodies orantigen-binding fragments (optionally monoclonal antibodies orfragments) described herein can be introduced into a cell bytransfection, transformation, or transduction.

IV. Pharmaceutical Compositions and Methods of Using Combinations ofAnti-Staphylococcus aureus Antibodies

The present disclosure provides a composition comprising an effectiveamount of any one or combination of the antibodies or antigen-bindingfragments thereof described herein and a pharmaceutically acceptablecarrier. In one embodiment, for example, the composition may comprise afirst antibody or antigen-binding fragment thereof (optionallymonoclonal) that specifically binds to S. aureus alpha toxin protein, asdescribed above, a second antibody or antigen-binding fragment thereof(optionally monoclonal) that specifically binds to S. aureus ClfAprotein, and a third antibody or antigen-binding fragment thereof(optionally monoclonal) that specifically binds to at least one S.aureus leukotoxin, as described above, and a pharmaceutically acceptablecarrier. Alternatively, the composition can comprise a pharmaceuticallyacceptable carrier and any one or any two of (i) an antibody orantigen-binding fragment thereof that specifically binds to S. aureusAT, (ii) an antibody or antigen-binding fragment thereof thatspecifically binds to S. aureus ClfA, (iii) an antibody orantigen-binding fragment thereof that specifically binds to at least oneS. aureus leukotoxin.

In another aspect, the composition may comprise the nucleic acidsequences encoding the AT-binding antibody or antigen-binding fragment,the ClfA-binding antibody or antigen-binding fragment, and/or theleukotoxin-binding antibody or antigen-binding fragment, or one or morevectors comprising such nucleic acid sequences. In one aspect, thecomposition is a pharmaceutically acceptable (e.g., physiologicallyacceptable) composition, which comprises a carrier, such as apharmaceutically acceptable (e.g., physiologically acceptable) carrierand the AT-binding antibody or antigen-binding fragment, theClfA-binding antibody or antigen-binding fragment, and/or theanti-leukotoxin antibody or antigen-binding fragment nucleic acidsequence(s), or vector(s).

Any suitable carrier can be used within the context of the disclosure,and such carriers are well known in the art. The choice of carrier willbe determined, in part, by the particular site to which the compositionmay be administered and the particular method used to administer thecomposition. The composition optionally can be sterile. The compositioncan be frozen or lyophilized for storage and reconstituted in a suitablesterile carrier prior to use. The compositions can be generated inaccordance with conventional techniques described in, e.g., Remington:The Science and Practice of Pharmacy, 21st Edition, Lippincott Williams& Wilkins, Philadelphia, Pa. (2001).

The composition desirably comprises the AT-binding antibody orantigen-binding fragment, the ClfA-binding antibody or antigen-bindingfragment, and the leukotoxin-binding antibody or antigen-bindingfragment in an amount that is effective to treat or prevent a S. aureusinfection. In another aspect, the composition comprises the AT-bindingantibody or antigen-binding fragment in an amount that is effective totreat or prevent a S. aureus infection in combination with theClfA-binding antibody or antigen-binding fragment, and theleukotoxin-binding antibody or antigen-binding fragment. In anotheraspect, the composition comprises the ClfA-binding antibody orantigen-binding fragment in an amount that is effective to treat orprevent a S. aureus infection in combination with the AT-bindingantibody or antigen-binding fragment, and the leukotoxin-bindingantibody or antigen-binding fragment. In another aspect, the compositioncomprises the leukotoxin-binding antibody or antigen-binding fragment inan amount that is effective to treat or prevent a S. aureus infection incombination with the AT-binding antibody or antigen-binding fragment,and the ClfA-binding antibody or antigen-binding fragment. In anotheraspect, the composition comprises the AT-binding antibody orantigen-binding fragment and the ClfA-binding antibody orantigen-binding fragment in an amount that is effective to treat orprevent a S. aureus infection in combination with the leukotoxin-bindingantibody or antigen-binding fragment. In another aspect, the compositioncomprises the AT-binding antibody or antigen-binding fragment and theleukotoxin-binding antibody or antigen-binding fragment in an amountthat is effective to treat or prevent a S. aureus infection incombination with the ClfA-binding antibody or antigen-binding fragment.In another aspect, the composition comprises the ClfA-binding antibodyor antigen-binding fragment and the leukotoxin-binding antibody orantigen-binding fragment in an amount that is effective to treat orprevent a S. aureus infection in combination with the AT-bindingantibody or antigen-binding fragment.

To this end, the disclosed method comprises administering atherapeutically effective amount or prophylactically effective amount ofan AT-binding antibody or antigen-binding fragment thereof, aClfA-binding antibody or antigen-binding fragment thereof, and aleukotoxin-binding antibody or antigen-binding fragment thereof or acomposition comprising any one or any combination of the aforementionedantibodies or fragments (including monoclonal antibodies or fragments).

The disclosure provides a method of treating or preventing aStaphylococcus aureus (S. aureus) infection in a subject (e.g., ahuman), which comprises administering the AT-binding antibody orantigen-binding fragment, the ClfA-binding antibody or antigen-bindingfragment, and/or the leukotoxin-binding antibody or antigen-bindingfragment described herein to a subject in need thereof, whereupon the S.aureus infection is treated or prevented in the subject. The disclosurealso provides use of the AT-binding antibody or antigen-bindingfragment, the ClfA-binding antibody or antigen-binding fragment, and/orthe leukotoxin-binding antibody or antigen-binding fragment, describedherein, or the composition comprising any one or combination of theantibodies or fragments thereof described herein, in the manufacture ofa medicament for treating or preventing a S. aureus infection.

As discussed herein, Staphylococcus aureus is a major human pathogenthat causes a wide range of clinical infections. S. aureus is a leadingcause of bacteremia and infective endocarditis as well asosteoarticular, skin and soft tissue, pleuropulmonary, anddevice-related infections. Approximately 30% of the human population iscolonized with S. aureus (Wertheim et al., Lancet Infect. Dis., 5:751-762 (2005)). The symptoms of S. aureus skin infections include, forexample, boils, cellulits, and impetigo. S. aureus also may cause foodpoisoning, blood poisoning (also known as bacteremia), toxic shocksyndrome, and septic arthritis. The epidemiology, pathophysiology, andclinical manifestations of S. aureus infections are described in detailin, e.g., Tong et al., Clin. Microbiol. Rev., 28(3): 603-661 (2015), andthe genomes of several different S. aureus strains have been sequenced(see, e.g., GenBank/EMBL Accession Nos. BX571856, BX571857, BX571858,FN433596, FN433597, FN433598, HE681097, FR821777, FR821778, FR821779,and FR821780). As discussed herein, the subject (e.g., human subject)can have diabetes.

In certain instances, a therapeutically effective amount of theAT-binding antibody or antigen-binding fragment, the ClfA-bindingantibody or antigen-binding fragment, and/or the leukotoxin-bindingantibody or antigen-binding fragment, is an amount which inhibits S.aureus-associated sepsis, inhibits S. aureus agglutination, inhibitsthromboembolic lesion formation, neutralizes alpha toxin, neutralizesLukSF, HlgAB, HlgCB and LukED, induces opsonophagocytosis, inhibits S.aureus fibrinogen binding, inhibits S. aureus agglutination, or anycombination of the foregoing, in a human.

Alternatively, the pharmacologic and/or physiologic effect may beprophylactic, i.e., the effect completely or partially prevents adisease or symptom thereof. In this respect, the disclosed methodcomprises administering a “prophylactically effective amount” of theAT-binding antibody or antigen-binding fragment, the ClfA-bindingantibody or antigen-binding fragment, and/or the leukotoxin-bindingantibody or antigen-binding fragment, (including monoclonal antibodiesor fragments).

Therapeutic or prophylactic efficacy can be monitored by periodicassessment of treated patients. For repeated administrations overseveral days or longer, depending on the condition, the treatment can berepeated until a desired suppression of disease symptoms occurs.However, other dosage regimens may be useful and are within the scope ofthe present disclosure. The desired dosage can be delivered by a singlebolus administration of the composition, by multiple bolusadministrations of the composition, or by continuous infusionadministration of the composition.

The method of treating or preventing a S. aureus infection can compriseadministering the AT-binding antibody or antigen-binding fragment, theClfA-binding antibody or antigen-binding fragment, and/or theleukotoxin-binding antibody or antigen-binding fragment in the samecomposition or in separate compositions. When separate compositions areadministered to the subject, each of the compositions can beadministered simultaneously or sequentially in any order.

The composition(s) comprising an effective amount of any one orcombination of the antibodies described herein, or antigen-bindingfragments thereof, the nucleic acid sequence(s) encoding any of theforegoing, or the vector comprising the nucleic acid sequence can beadministered to a subject, such as a human, using standardadministration techniques, including intravenous, intraperitoneal,subcutaneous, and intramuscular administration routes. The compositionmay be suitable for parenteral administration. The term “parenteral,” asused herein, includes intravenous, intramuscular, subcutaneous, andintraperitoneal administration. In some embodiments, the composition isadministered to a subject using peripheral systemic delivery byintravenous, intraperitoneal, or subcutaneous injection.

The AT-binding antibody or antigen-binding fragment, the ClfA-bindingantibody or antigen-binding fragment, and/or the leukotoxin-bindingantibody or antigen-binding fragment or composition(s) comprising same,can be administered alone or in combination with other drugs (e.g., asan adjuvant) conventionally used for treating S. aureus infections. Thecomposition(s) comprising the AT-binding antibody or antigen-bindingfragment, the ClfA-binding antibody or antigen-binding fragment, and/orthe leukotoxin-binding antibody or antigen-binding fragment can be usedin combination with, for example, one or more antibiotics, such as apenicillinase-resistant β-lactam antibiotic (e.g., oxacillin orflucloxacillin). Gentamicin can be used to treat serious infections,such as endocarditis. Most strains of S. aureus, however, are nowresistant to penicillin, and two in 100 people carrymethicillin-resistant strains of S. aureus (MRSA). MRSA infectionstypically are treated with vancomycin, and minor skin infections can betreated with triple antibiotic ointment.

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

Example 1

This example demonstrates that antibodies that bind to alpha toxin (AT),clumping factor A (ClfA), and leukotoxins do not interfere with eachother's in vitro activities when used in combination.

Several experiments were conducted to determine if using antibodies thatbind to AT, ClfA, and leukotoxins in combination would interfere withthe activity of any of these individual assays. In these experiments,the MEDI4893*, SAR114, and SAN481-SYT* antibodies were used incombination and are collectively referred to as “MEDI6389.”

A red blood cell (RBC) hemolysis inhibition assay was performed todetermine if the anti-ClfA SAR114 or the anti-leukotoxin SAN481-SYT*antibodies interfered with the activity of MEDI4893*. Washed rabbit redblood cells (50 μl) were incubated with native alpha toxin (0.1 μg/ml in25 μl) and serial dilution of 25 μl of MEDI4893*, SAN481_SYT*+SAR114 ormAb trio combination (MEDI6389) as indicated on FIG. 2. Irrelevant mAbc-IgG was used as negative control. After 2 hrs incubation at 37° C.,hemoglobin release was measured in 50m1 supernatants at OD450 nm. %hemolysis inhibition was measured as:100*[(OD_(AT+mAb))/(OD_(AT alone))]. The results, shown in FIG. 2 and inTable 1, below, demonstrate that the use of the three antibodies incombination (MED6389) was about equally effective in inhibiting RBChemolysis as MEDI4893* alone.

A monocyte viability assay was performed to determine if the anti-ATMEDI4893* or the anti-ClfA SAR114 antibodies interfered with theactivity of SAN481-SYT*. Human monocytic cell line HL-60 (5e4/well/25μl) were incubated for 2 hrs at 37° C. with a mix of LukS+LukF (100ng/ml each) and serial dilution as indicated on FIG. 3 of SAN481_SYT*,MEDI4893*+SAR114, or mAb trio combination (MEDI6389). Irrelevant mAbc-IgG was used as negative control. Cell viability was quantified bymeasuring luminescent signal in a Cell Glo assay (Promega) followingcompany instructions. % viability was calculated as followed:100*[(OD_(cells+LukSF+mAb))/(OD_(cells alone))]. The results, shown inFIG. 3 and in Table 1, below, demonstrate that the use of the threeantibodies in combination (MED6389) was about equally effective inmaintaining monocyte viability as SAN481-SYT* alone.

A fibrinogen-binding inhibition assay was performed to determine if theanti-AT MEDI4893* or the anti-leukotoxin SAN481-SYT* antibodiesinterfered with the activity of SAR114. Fibrinogen coated 96 well plate(4 μg/ml) was blocked with PBS 2% BSA, and after washes incubated for 1hr at room temperature with a biotinylated ClfA001 (2 μg/ml) and serialdilution of SAR114, MEDI4893*+SAN481_SYT*, or mAb trio combination(MEDI6389) as indicated on FIG. 4. After 3 washes, plates were incubatedwith streptavidin-phycoerythrin at 1:10 000 for 1 hr, and OD_(450 nm)read following addition of 100 μl TMB, and then 100 μl of H₂SO₄ 0.2M.Irrelevant mAb c-IgG was used as negative control. The percentage (%) offibrinogen binding inhibition was calculated as:100*[(OD_(ClfA+mAb))/(OD_(ClfA alone))]. The results, shown in FIG. 4and in Table 1, below, demonstrate that the use of the three antibodiesin combination (MED6389) was about equally effective in inhibitingfibrinogen binding as SAR114 alone.

TABLE 1 IC50 (μg/ml) MEDI4893* SAN481-SYT* SAR114 MEDI6389 RBC assay0.1731 0.1635 Monocyte viability 0.225 0.2246 Fg binding 3.02 2.63

The use of the combination of the three antibodies (MEDI6389) did notinhibit the activity of MEDI4893 in the RBC assay, the activity ofSAN481* in the monocyte viability assay, or the Fg binding of SAR114.

Example 2

This example demonstrates that the combination of antibodies that bindto alpha toxin (AT) and leukotoxins is superior to either antibody alonein a wound healing model.

In these experiments, 6-7 week old female Balb/c mice (n=5) wereimmunized intra-peritoneally with (i) 0.5 mg/kg a control antibody(c-IgG), (ii) 0.1 mg/kg of the anti-AT antibody MEDI4893*, (iii) 0.5mg/kg of the anti-leukotoxin antibody SAN481-SYT*, or (iv) bothMEDI4893* (0.1 mg/kg) and SAN481-SYT* (0.5 mg/kg). The mice were thenintradermally infected 24 hrs later with a wound isolate 1447526 (5e7cfu in 50 μl PBS).

Lesions were monitored over 17 days, and the results are shown in FIG.5. Lesion sizes were significantly smaller in mice treated with thecombination of anti-AT and anti-leukotoxin antibodies than in micetreated with either antibody alone (p<0.05 and indicated with a (*).Pictures on FIG. 5 shows lesions at day 7 post-infection.

Example 3

This example demonstrates that neutralization of alpha toxin (AT),clumping factor A (ClfA), and leukotoxins are all necessary for in vivoprotection in the rabbit bacteremia model.

In these experiments, 3-month old female rabbits (n=7) receivedintravenous administration of (i) a control IgG antibody, (ii) theanti-leukotoxin antibody SAN481-SYT*, (iii) SAN481-SYT* and theanti-ClfA antibody SAR114, (iv) SAR114 and the anti-AT antibodyMEDI4893*, (v) SAN481-SYT* and MEDI4893*, or (vi) SAN481-SYT*, SAR114and MEDI4893*, i.e., MEDI6389. All antibodies were administered at 5mg/kg, other than the control antibody, which was administered at 15mg/kg. The rabbits were then infected 12 hours later with intravenousCA-MRSA SF8300.

Survival was monitored over four days after challenge, and thecombination of SAN481-SYT*, SAR114 and MEDI4893* (MEDI6389) orMEDI4893*+SAN481_SYT* significantly improved survival over c-IgG asshowed by a Log Rank Mantel-Cox statistical test (p=0.0001). The resultsare shown in FIG. 6. Notably, neither targeting AT and ClfA nortargeting leukotoxins is sufficient for protection in this rabbit lethalbacteremia model.

Example 4

This example demonstrates that neutralization of alpha toxin (AT),clumping factor A (ClfA), and leukotoxins are all necessary for in vivoprotection in the rabbit bloodstream infection model.

In these experiments, 3-month old female rabbits (n=12) receivedintravenous administration of 15 mg/kg of (i) a control IgG antibody,(ii) the anti-leukotoxin antibody SAN481-SYT*, (iii) the anti-ClfAantibody SAR114 and the anti-AT antibody MEDI4893*, (iv) SAN481-SYT* andMEDI4893*, or (vi) SAN481-SYT*, SAR114 and MEDI4893*, i.e., MEDI6389.The rabbits were then infected 12 hours later with intravenous HA-MRSANRS382 or CA-MRSA SF8300.

Survival was monitored over four days after challenge, and the resultsare shown in FIG. 7. The combination of SAN481-SYT*, SAR114 andMED14893*(MEDI6389) or MEDI4893*+SAN481_SYT* significantly improvedsurvival over c-IgG as showed by a Log Rank Mantel-Cox statistical test(p=0.0015 for NRS382 and p=0.0001 for SF8300) was most effective inincreasing survival as a result with either HA-MRSA NRS382 or CA-MRSASF8300 bacteria.

Example 5

This example demonstrates that a combination of antibodies that bind toalpha toxin (AT), clumping factor A (ClfA), and leukotoxins (MEDI6389)improves wound healing resulting from mixed-bacterial infections in adiabetic mouse dermonecrosis model.

Mixed-bacterial infections were compared to infections caused by asingle bacteria in seven week male (n=10) type 2 diabetic mice(BKS.Cg-m+/+Lepr^(db)) mice. The mice were infected intra-dermally witha mixture of S. aureus (SA; 5e6 cfu), Pseudomonas aeruginosa (A; 5 cfu)and Streptococcus pyogenese (SP; 1e1 cfu) under 50 μl in PBS, or with SA(5e6 cfu). The lesion sizes were monitored over 43 days. The results,shown in FIG. 8, demonstrate that the mixed infections result in delayin the time of wound closure in this diabetic mouse dermonecrosis modelas compared to infections that result from SA alone.

The effect of the MEDI6389 combination (comprising anti-AT mAbMEDI4893*, anti-ClfA mAb SAR114, and anti-leukotoxin mAb SAN481_SYT*) onthe time of wound closure and bacteria load was examined. Mice werepassively immunized intra-peritoneally with MEDI6389 (each mAb at 15mg/kg) or control IgG c-IgG (15 mg/kg) and infected intra-dermally 24hrs later with SA/SP/PA. Lesions were followed over 43 days, andbacteria counts were enumerated at days 7, 14, and 21 in skin lesions.The results, shown in FIG. 9, demonstrate that MED6389 increases woundhealing and decreases bacteria counts in mixed-bacterial skin lesions inthis diabetic mouse dermonecrosis model.

Example 6

This example provides the materials and methods used in Examples 7-11.

In Vivo Model of Systemic Infection

Frozen stock cultures of S. aureus USA300 strain SF8300 were thawed anddiluted to the appropriate inoculum in sterile PBS, pH 7.2 (Invitrogen)(Hua et al., Antimicrob Agents Chemother. 58:1108-17 (2014)).Specific-pathogen-free 7- to 8-week-old femaleBKS.Cg-Dok7<m>+/+Lepr,db>/J (db/db), C57BKS, C57BL/6J-STZ, and C57BL/6Jmice (The Jackson Laboratory) were briefly anesthetized and maintainedin 3% isoflurane (Butler Schein™ Animal Health) with oxygen at 3 L/minand infected intravenously. All bacterial suspensions were administeredin 100 μL of PBS. In select experiments, neutralizing antibodiesMEDI4893*, anti-αVβ6/8, anti-αVβ6, c-IgG (MedImmune antibodies),anti-TGFβ (clone 1D11.16.8, BioXcell), or control mouse IgG1 wereadministered (15 mg/kg) in 0.5 mL intraperitoneally (IP) 24 hours priorto infection. Rosiglitazone (Sigma-Aldrich) was administered (10 mg/kg)orally for 7 days. Mice were infected 24 hours following the final doseof rosiglitazone. Animals were euthanized with CO₂ at the indicated timepoints, and blood, liver, or kidneys were collected for analysis. Thebacterial load in kidneys was determined by plating serial dilutions onTSA.

NET ELISA

To measure NETs, a hybrid of 2 different ELISA kits were used. Plateswere initially coated with anti-elastase capture antibody (R&D Systems).Fresh serum samples were added to the coated wells, then incubated, andwashed. Next, anti-DNA-POD antibody (Roche) was used to detect DNA inthe captured proteins in the wells. Plates were developed with ABTSsolution and ABTS stop solution. Absorbances were measured at 405 nm ona plate reader using SoftMax Pro software.

HDN and LDN Purification

High and low density neutrophils (HDN and LDN) were isolated from wholeblood. Following sacrifice, blood was collected and layered over withhistopaque 1077 (Sigma-Aldrich). Cells were separated by centrifugation(500 g, 30 minutes). The lower fraction was treated with ACK lysisbuffer (Thermo Fisher Scientific) to remove red blood cells from thehigh density neutrophils. The upper (PBMC) fraction was washed 2× withPBS, and low density neutrophils were isolated with the EasySep MouseNeutrophil Enrichment Kit (Stemcell Technologies). Purified cellpopulations were lysed for protein or RNA analysis.

Flow Cytometry

Either whole blood or purified low density cells, were washed twice inice-cold FACs buffer (PBS with 5% fetal bovine serum, and 0.1% sodiumazide). Fc receptors were blocked with anti-mouse CD16/CD32(eBioscience), and cells were stained with antibodies against mouse CD45(PE conjugated, clone FA-11), CD11c (APC-Cy5.5 or FITC conjugated, cloneN418), CD11b (BV605 conjugated, clone M1/70), Ly6-G (BV421 or PE-Cy7conjugated, clone 1A8), and Ly6-C. Cells were imaged using the LSR IIFlow Cytometer (BD Biosciences) and analyzed with FlowJo. A knownconcentration of counting beads (Bangs Laboratories) was added to eachsample to calculate the number of cells.

Western Blotting

Cells were lysed with Ripa buffer (ThermoFisher Scientific) containingcomplete protease inhibitor (Sigma) and frozen. In select experiments,IP3R was immunoprecipitated using anti-IP3R (Abcam cat #ab5804) and theDynabeads protein G immunoprecipitation kit (ThermoFisher Scientific).Equal amounts of protein were separated on 4-12% bis-Tris NuPage gelsand transferred to PVDF membranes (ThermoFisher Scientific).Immunodetection was performed using anti-H3Cit (Abcam cat #ab5103),anti-lactoferrin (Abcam cat #ab77705), anti-MMP9 (Abcam cat #ab38898),anti-IP3R (Abcam cat #ab5804), anti-P-Ser/Thr (Abcam cat #ab17464), andanti-actin (Sigma cat #A3854). Proteins were visualized with the Odysseyimaging system (Li-COR).

Example 7

This example demonstrates that elevated glucose levels correlate withmore severe S. aureus infections.

Two models of murine diabetes, STZ induced and db/db, were used to studythe effect of diabetes on the systemic response to systemic infectionwith S. aureus. In each model, the diabetic mice had a non-fastingglucose level greater than 450 dg/mL, while non-diabetic control levelswere less than 200 dg/mL. Mice were infected with 5e7 CFU S. aureus(USA300, SF8300). CFU were collected from the kidney 48 hours postinfection, and mortality was monitored for 14 days. Increased mortalitywas observed in both STZ (P=0.0011) and db/db (P=0.0241) models ascompared with non-diabetic control (FIGS. 11A and 11B). Of note, thisdid not correlate with a difference in bacterial CFU recovered from thekidneys 48 hours post-infection (FIGS. 11C and 11D). To confirm thatincreased mortality was a consequence of elevated glucose in thediabetic host, mice were treated with Rosiglitazone for 1 week prior toinfection to reduce circulating glucose levels (FIG. 11E). Rosiglitazonesignificantly reduced mortality (P=0.0041) following infection with S.aureus, however the bacterial burden in the kidney was unaffected (FIGS.11F and 11G).

It is notable that no clearance defect was observed in the diabetic miceas compared with non-diabetic controls. This highlights the contributionof excessive inflammation or exaggerated host response to the increasein mortality.

Example 8

This example demonstrates that enhanced NEToisis occurs in diabeticmice.

Neutrophils in a diabetic host, or in the presence of elevated glucoselevels, are increasingly prone to NETosis. In the diabetic population,NET release has been shown to impair wound healing in mice, and thepresence of NETs in the serum correlates with non-healing wounds inpatients (Fadini, G. P. et al., Diabetes 65: 1061-1071 (2016) and Wong,S. L. et al., Nat Med 21: 815-819 (2015)). Neutrophils also release NETsin response to bacterial infection, therefore it was hypothesized thatS. aureus infection would result in increased systemic NET release indiabetic mice. Complexes of neutrophil elastase and double stranded DNAare used as a measurement of NET formation and quantified by ELISA(Fadini, G. P. et al., Diabetes 65: 1061-1071 (2016)). Significantincreases (P=0.0003) in serum NETs were observed in diabetic miceintravenously infected with S. aureus for 24 hours, while significantincreases were not observed in non-diabetic control mice (FIG. 12A).Levels of circulating NETs were not different in uninfected diabetic andnon-diabetic mice.

Alpha toxin (AT), once released by S. aureus, binds to the receptorADAM10 on the surface of platelets. (Neutrophils do not express ADAM10.)In response to AT, platelets aggregate and bind to circulatingneutrophils, resulting in activation of caspase-1 mediated signaling andNET production (Powers, M. E. et al., Cell Host Microbe 17: 775-787(2015) and Surewaard, B. G. J. et al. Cell Host Microbe 24: 271-284(2018)). Consistent with these findings, neutralization of AT withmonoclonal antibody MEDI4893* significantly reduced the number of NE-DNAcomplexes in the serum 48 hours post-infection in diabetic animals (FIG.12B). Increased AT-dependent NET production was confirmed 48 hourspost-infection by increased citrinulated Histone H3 (H3cit) in the liveras detected by western blot (FIG. 12C) Visualization of liver sectionsimmunohistochemically stained with anti-Ly6G to mark neutrophils andanti-H3cit also showed increased AT-dependent NET (i.e., less anti-H3cit staining in the livers of mice that received MEDI4893*) (Cohen T S,et al. Staphylococcus aureus drives expansion of low density neutrophilsin diabetic mice. JCI 2019 IN PRESS). Neutralization of AT significantlyincreased survival (P=0.0255) of diabetic mice infected with S. aureus(FIG. 12D). These data indicate that systemic infection of the diabetichost lead to an AT-dependent increase in circulating NETs that can beinhibited by MEDI4893*.

Example 9

This example demonstrates that low density neutrophils correlate withincreased NETosis.

Similar to macrophages, neutrophils can be separated into differentclasses based on functional characteristics. Severe burns have beenshown to alter the phenotype of circulating neutrophils and to alter TLRexpression, cytokine production, and their ability to drive macrophagepolarization (Tsuda, Y. et al. Immunity 21: 215-226 (2004)). Neutrophilsare unique in that they can also be separated by cell density. Highdensity neutrophils are anti-tumor, phagocytic cells, while low densityneutrophils are considered pro-tumor phagocytic defective cells (Sagiv,J. Y. et al. Cell Rep 10: 562-573 (2015)). While Tsuda et. al. did notmeasure the density of neutrophils isolated from mice susceptible to S.aureus infection, the shape of the nuclei in these neutrophils wassimilar to the shape of nuclei in low density cells (Sagiv, J. Y. et al.Cell Rep 10: 562-573 (2015) and Fridlender, Z. G. et al. Cancer Cell 16:183-194 (2009)). The shapes of the nuclei in neutrophils taken fromnon-diabetic mice and diabetic mice also had striking differences. Thenucleus in cells isolated from non-diabetic mice were multilobular orround, while large numbers of cells with ringed nuclei were observed inthe blood of diabetic mice (Cohen T S, et al. Staphylococcus aureusdrives expansion of low density neutrophils in diabetic mice. JCI 2019IN PRESS). These structures were similar to those reported by Tsuda et.al to be found in the cells isolated from S. aureus susceptible mice,indicating that diabetic mice could have an increased number of lowdensity, or immune impaired neutrophils.

Hyper NET production is a characteristic of low density neutrophils(LDN), and it was hypothesized that higher numbers of LDNs in infecteddiabetic mice were responsible for the increases in NETs (Villanueva, E.et al. J Immunol 187: 538-552 (2011)). Blood was collected from C57BKSand db/db mice 48 hours post-IV infection and was analyzed for presenceof LDNs. The amount of LDNs in the blood of infected db/db mice wassignificantly increased compared to uninfected db/db mice (P<0.0001) aswell as infected C57BKS control mice (P=0.0003) (FIG. 13A). Increases inLDNs were not observed in C57BKS mice (FIG. 13A). Similar increases wereobserved in STZ induced diabetic mice and not in C57BL/6 controls (FIG.14). Lowering glucose levels with Rosiglitazone prior to infectionsignificantly (P=0.0116) reduced LDNs 48 hours post-infection (FIG.13B).

To ensure that the observations were not based on degranulatedneutrophils, LDNs and high density neutrophils (HDNs) were isolated fromthe blood of infected db/db mice, and the amounts of lactoferrin(secondary granules) and MMP9 (tertiary granules) were measured bywestern blot. Equivalent amounts of both were observed, indicating thatLDNs have similar granular content as compared to HDNs (Cohen T S, etal. Staphylococcus aureus drives expansion of low density neutrophils indiabetic mice. JCI 2019 IN PRESS). Neutralizing AT prevented systemicNET release, therefore the influence of AT on the number of LDNs wasassessed. LDNs in the blood of db/db mice treated 24 hours prior toinfection with c-IgG or MEDI4893* and infected with S. aureus for 48hours were measured. A significant reduction in LDNs in miceprophylactically treated with MEDI4893* (FIG. 13C) was observed, whileoverall numbers of neutrophils were not affected (FIG. 13D), indicatingthat AT contributes to the increase in LDNs.

These data indicate that LDNs contribute to the pathology associatedwith diabetic S. aureus infection and that these LDNs are associatedwith excessive NET release in both the liver, a key target organ ofsystemic infections, and systemically in the blood. Moreover, MEDI4893*reduces LDNs in diabetic mice.

Example 10

This example demonstrates that TGFβ drives expansion of LDNs.

TGFβ has been implicated as a central regulator of neutrophil phenotype,and in tumor models it can drive a phenotypic switch from high to lowdensity neutrophil (Sagiv, J. Y. et al. Cell Rep 10: 562-573 (2015) andFridlender, Z. G. et al. Cancer Cell 16: 183-194 (2009). Sagiv et. al.demonstrated that the addition of TGFβ to blood taken from tumor bearingmice, not naïve mice, will increase numbers of LDNs in vitro (id.). Thisstudy was repeated with blood from non-diabetic and diabetic mice. Theaddition of TGFβ to diabetic blood significantly increased (P=0.0021)the number of LDNs (FIG. 15A). The same was not observed in non-diabeticblood. Based on this in vitro evidence demonstrating that TGFβ canincrease numbers of LDNs, its necessity for their induction by blockingin vivo was tested. Diabetic mice were prophylactically treated withneutralizing TGFβ antibody 24 hours prior to infection with S. aureus.The numbers of LDNs in the bloodstream was significantly reduced(P=0.0003) by inhibition of TGFβ, while numbers of bacteria in thekidneys were similar between groups (FIGS. 15B and 15C). Survival wassignificantly improved (P=0.0072) by neutralizing TGFβ (FIG. 15D).Visualization of NETs in the liver demonstrated a loss of NETs when TGFβwas neutralized (Cohen T S, et al. Staphylococcus aureus drivesexpansion of low density neutrophils in diabetic mice. JCI 2019 INPRESS). These data suggest that reducing LDNs by blocking TGFβ couldpromote survival.

TGFβ is secreted as a pro-form protein (pro-TGFβ) and requires cleavageto be activated. Binding of pro-TGFβ by αVβ8 integrin has been linked toits activation and prevention of colitis, and its expression ondendritic cell and monocyte subsets is increased in response toinflammation (Travis, M. A. et al. Nature 449: 361-365 (2007) and Kelly,A. et al. J Exp Med, doi:10.1084/jem.20171491 (2018)). To determine ifS. aureus infection influences expression of αVβ8 integrin, innateimmune cells were isolated from the liver and spleen of C57BKS and db/dbmice 24 hours post-infection, and the expression of αVβ8 was analyzed byflow cytometry. Numbers of 38 positive inflammatory monocytes anddendritic cells increased in the livers of db/db mice, not C57BKS mice,following infection (FIG. 16A). Interestingly, while integrin expressionincreased on the surface of monocytes, it was the overall number of DCsthat increased, not the density of 38 (FIG. 16B). To demonstrate thefunctional relevance of αVβ8 in this model, mice were prophylacticallytreated with antibodies neutralizing αVβ6/8, αVβ6 or c-IgG and infectedwith S. aureus. Forty-eight hours post infection LDNs were significantlydecreased (P=0.0090) in the bloodstream in the mice treated with αVβ6/8neutralizing antibody compared with c-IgG (FIG. 16C). Neutralization ofαVβ6 alone did not reduce the numbers of these cells. Integrininhibition did not affect the numbers of bacteria in the kidneys 48hours post-infection (FIG. 16D). Survival was significantly improved inmice treated with anti-αVß6/8 antibody as compared with c-IgG treatedmice (FIG. 16E). Therefore, consistent with directly neutralizing TGFβ,blocking the integrin responsible for activating this pathway wasprotective in diabetic mice.

These data show that neutralization of either αVß6/8 or TGFβ preventsLDN increases and reduces mortality. These data also show that dendriticcells play a central role in the pathogenesis of diabetic infection dueto their ability to activate TGFβ and promote expansion of LDNs.

Example 11

This example demonstrates that AT drives TGFβ activation.

It was hypothesized that AT was influencing LDN numbers by affecting theTGFβ pathway. Following its activation, TGFß binds to its receptorcomplex, activates SMAD transcription factors, and drives expression ofdownstream genes. Therefore, activation of SMAD signaling is commonlyused as a surrogate measurement of TGFβ activation. pSMAD levels wereanalyzed in the livers of diabetic and non-diabetic mice that wereinfected (24 hours) with S. aureus. Significantly increased pSMAD wasobserved in the livers of infected diabetic mice as compared to naïvediabetic mice (P<0.0001) and infected non-diabetic mice (P=0.0338) (FIG.17A). In diabetic mice, MEDI4893* significantly reduced (P<0.0001) pSMADlevels in the liver, indicating that AT was contributing to activationof TGFβ signaling (FIG. 17B). Neutralizing AT did not alter the numbersof αVβ8 expressing innate immune cells (FIG. 17C). These data indicatethat AT influences activation of TGFβ through a mechanism that isindependent of αVβ8 expression on innate immune cells. Accordingly,neutralization of AT, which is a key S. aureus virulence factor, limitsactivation of TGFβ signaling, and subsequently reduces LDN numbers andNET release.

These data indicate that, in addition to binding to ADAM10 on platelets,AT can act through a second pathway that alters the neutrophil phenotypeand subsequent response to S. aureus infection. In the diabetic host,AT-dependent activation of TGFß signaling drives expansion of LDNs.Thus, AT is both promoting the expansion of the LDN population whichspontaneously release NETs and activating platelets, which can bind andfurther activate neutrophils.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A method of preventing a Staphylococcus aureus (S. aureus) infectionin a subject comprising administering to the subject (a) an antibody orantigen-binding fragment thereof that binds to S. aureus alpha toxin(AT), (b) an antibody or antigen-binding fragment thereof that binds toS. aureus clumping factor A (ClfA), and (c) an antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin.
 2. A method of treating or preventing a Staphylococcusaureus (S. aureus) infection in a subject comprising administering tothe subject an antibody or antigen-binding fragment thereof that bindsto at least one S. aureus leukotoxin and (a) an antibody orantigen-binding fragment thereof that binds to S. aureus alpha toxin(AT) or (b) an antibody or antigen-binding fragment thereof that bindsto S. aureus clumping factor A (ClfA).
 3. A composition comprising (a)an antibody or antigen-binding fragment thereof that binds to S. aureusAT, (b) an antibody or antigen-binding fragment thereof that binds to S.aureus ClfA, and (c) an antibody or antigen-binding fragment thereofthat binds to at least one S. aureus leukotoxin.
 4. A compositioncomprising an antibody or antigen-binding fragment thereof that binds toat least one S. aureus leukotoxin and (a) an antibody or antigen-bindingfragment thereof that binds to S. aureus AT or (b) an antibody orantigen-binding fragment thereof that binds to S. aureus ClfA. 5-12.(canceled)
 13. The method of claim 1, wherein the antibody orantigen-binding fragment thereof that binds to S. aureus AT binds to thesame S. aureus AT epitope as an antibody comprising a VH comprising theamino acid sequence of SEQ ID NO:19 and a VL comprising the amino acidsequence of SEQ ID NO:33.
 14. The method of claim 1, wherein theantibody or antigen-binding fragment thereof that binds to S. aureus ATcompetitively inhibits binding of an antibody comprising a VH comprisingthe amino acid sequence of SEQ ID NO:19 and a VL comprising the aminoacid sequence of SEQ ID NO:33 to S. aureus AT.
 15. The method of claim1, wherein the antibody or antigen-binding fragment thereof that bindsto S. aureus AT comprises a variable heavy chain (VH) complementaritydetermining region (CDR) 1 comprising the amino acid sequence of SEQ IDNO:1, a VH CDR2 comprising the amino acid sequence of SEQ ID NO:2, a VHCDR3 comprising the amino acid sequence of SEQ ID NO:3, a variable lightchain (VL) CDR1 comprising the amino acid sequence of SEQ ID NO:10, a VLCDR2 comprising the amino acid sequence of SEQ ID NO:11, and a VL CDR3comprising the amino acid sequence of SEQ ID NO:12. 16-19. (canceled)20. The method of claim 1, wherein the antibody or antigen-bindingfragment thereof that binds to S. aureus AT comprises the VH CDR1, VHCDR2, VH CDR3, VL CDR1, VL CDR2, and VL CDR3 of MEDI4893. 21-34.(canceled)
 35. The method of claim 1, wherein the antibody orantigen-binding fragment thereof that binds to S. aureus AT has anaffinity of 80-100 pM for S. aureus AT.
 36. The method of claim 1,wherein the antibody or antigen-binding fragment thereof that binds toS. aureus ClfA binds to the same S. aureus ClfA epitope as an antibodycomprising a VH comprising the amino acid sequence of SEQ ID NO:20 and aVL comprising the amino acid sequence of SEQ ID NO:34.
 37. The method ofclaim 1, wherein the antibody or antigen-binding fragment thereof thatbinds to S. aureus ClfA competitively inhibits binding of an antibodycomprising a VH comprising the amino acid sequence of SEQ ID NO:20 and aVL comprising the amino acid sequence of SEQ ID NO:34 to S. aureus ClfA.38. The method of claim 1, wherein the antibody or antigen-bindingfragment thereof that binds to S. aureus ClfA comprises a VH CDR1comprising the amino acid sequence of SEQ ID NO:4, a VH CDR2 comprisingthe amino acid sequence of SEQ ID NO:5, a VH CDR3 comprising the aminoacid sequence of SEQ ID NO:6, a VL CDR1 comprising the amino acidsequence of SEQ ID NO:13, a VL CDR2 comprising the amino acid sequenceof SEQ ID NO:14, and a VL CDR3 comprising the amino acid sequence of SEQID NO:15. 39-40. (canceled)
 41. The method of claim 1, wherein theantibody or antigen-binding fragment thereof that binds to S. aureusClfA comprises a heavy chain constant domain comprising the amino acidsequence of CSYHLC (SEQ ID NO:55).
 42. The method of claim 41, whereinsaid heavy chain constant domain comprises the amino acid sequence ofMHEACSYHLCQKSLSLS (SEQ ID NO:56). 43-45. (canceled)
 46. The method ofclaim 1, wherein the antibody or antigen-binding fragment thereof thatbinds to S. aureus ClfA comprises the VH CDR1, VH CDR2, VH CDR3, VLCDR1, VL CDR2, and VL CDR3 of SAR114-N3Y, 11H10, SAR72, SAR80, SAR113,SAR132, SAR352, SAR372, SAR510, SAR547, SAS1, SAS19, or SAS203. 47-65.(canceled)
 66. The method of claim 1, wherein the antibody orantigen-binding fragment thereof that binds to S. aureus ClfA hasbinding affinities (K_(D)) of less than 1 nM for all ClfA genotypes.67-69. (canceled)
 70. The method of claim 1, wherein the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin binds to the same S. aureus leukotoxin epitope as an antibodycomprising a VH comprising the amino acid sequence of SEQ ID NO:32 and aVL comprising the amino acid sequence of SEQ ID NO:46.
 71. The method ofclaim 1, wherein the antibody or antigen-binding fragment thereof thatbinds to at least one S. aureus leukotoxin competitively inhibitsbinding of an antibody comprising a VH comprising the amino acidsequence of SEQ ID NO:32 and a VL comprising the amino acid sequence ofSEQ ID NO:46 to the S. aureus leukotoxin.
 72. The method of claim 1,wherein the antibody or antigen-binding fragment thereof that binds toat least one S. aureus leukotoxin comprises a VHCDR1 comprising theamino acid sequence of SEQ ID NO:7, a VH CDR2 comprising the amino acidsequence of SEQ ID NO:8, a VH CDR3 comprising the amino acid sequence ofSEQ ID NO:9, a VL CDR1 comprising the amino acid sequence of SEQ IDNO:16, a VL CDR2 comprising the amino acid sequence of SEQ ID NO:17, anda VL CDR3 comprising the amino acid sequence of SEQ ID NO:18. 73-76.(canceled)
 77. The method of claim 1, wherein the antibody orantigen-binding fragment thereof that binds to at least one S. aureusleukotoxin comprises the VH CDR1, VH CDR2, VH CDR3, VL CDR1, VL CDR2,and VL CDR3 of SAN481-SYT. 78-93. (canceled)
 94. The method of claim 1,wherein the S. aureus infection is sepsis, bacteremia, pneumonia, ICUpneumonia, skin or soft tissue infection (SSTI), diabetic infection ofthe lower limbs, a diabetic foot ulcer (DFU), a bone infection, jointinfection, a device infection, a wound infection, a surgical siteinfection, osteomyelitis, and/or antibiotic-resistant S. aureus. 95-109.(canceled)
 110. The method of claim 1, wherein the treating orpreventing an S. aureus infection comprises inhibiting S. aureusagglutination, toxin neutralization, inducing opsonophagocytosis,inhibiting S. aureus fibrinogen binding, inhibiting S. aureusagglutination, inhibiting thromboembolic lesion formation, inhibiting S.aureus-associated sepsis, or any combination of the foregoing. 111-118.(canceled)
 119. The method of claim 1, wherein the antibody orantigen-binding fragment thereof that binds to S. aureus AT, theantibody or antigen-binding fragment thereof that binds to S. aureusClfA, and/or the antibody or antigen-binding fragment thereof that bindsto at least one S. aureus leukotoxin are administered in the samepharmaceutical composition.
 120. A method of treating or preventing a S.aureus infection in a subject with diabetes comprising administering tothe subject an antibody or antigen-binding fragment thereof that bindsto S. aureus AT. 121-160. (canceled)